Hello again,
My fellow physics friends get ready to start your... " Motors!" That's right, not engines. We are learning about motors right now. In this super short blog, I'm going to explain the function of each part of the motor, why we scrape the current carrying wire in a certain way, why the motor turns, and what it could be used for. I also include a short video of the small motor I built while in physics class.
Here is the big question I will be answering and the one to keep in mind while reading...
Big Question: How does a motor work?
Function of each part of the motor
Battery: The battery has an area of high energy and one of low energy, a difference in v. The difference in v means that when the circuit is complete current will flow from the area of high energy to the area of low energy.
Paper Clips: The paper clips loosely hold the wire connecting the battery to the wire, in order to complete the circuit. The complete circuit means there will be a difference in v and current will flow, since voltage causes current.
Wire: The current carrying wire feels a force in the magnetic field and spins.
Magnet: The function of the magnet is to create a magnetic field that'll put a force on the moving charges in the current carrying wire.
Rubber band: The function of the rubber band is to connect the paperclips to the battery, completing the circuit. The complete circuit allows for there to be a difference in v, which causes current to flow.
Why did you scrape the armature a specific way?
We scraped the wire either on the top or bottom of each side. When that is done, the wires is pushed away from us and cause a torque. If we scrapped both the top and the bottom, then there would be current flowing on the top and bottom of the current carrying wire. If there is current flowing through the top and bottom of each end of the wire, the wire will be pushed in one direction and then right back to its original position.
Why does the motor turn?
The motor turns because the current carrying wire is perpendicular to the magnetic field. When perpendicular, the moving charges feel a force The force causes a torque and allows the loop to spin.
Video of my motor
What my motor could be used for
Uses
My motor could be used to spin blades if they are attached to the current carrying wire. The blades could be used as a fan or a smoothie blender. I could also attach wheels to each end that could move a car.
Friday, April 24, 2015
Tuesday, April 14, 2015
Unit 6 Summary
Hello my physics friends! This unit has been a whirlwind! It went by so fast I'm still trying to catch my breath, to be honest. However, it was as exciting and captivating as always. In this unit we learned about...
1.) Charges and Polarization including Coulomb's Law
2.) Electric Fields
3.) Electric Potential/Electric Potential difference, Capacitors
4.) Ohm's Law and Electric Potential difference
5.) Types of current, source of Electrons, Power
6.) Parallel and Series Circuits
Part one: Charges and Polarization including Coulomb's Law
1.) What are the two types of charges?
The two types of charges are positive and negative.
2.) How does something become positive, negative, and neutral?
To become protons lose electrons. To become negative they lose electrons. To become neutral there is a balance of positive and negative charges.
3.) What do like charges do? What do unlike charges do?
The like charges repel while the opposite charges are attracted to each other.
4.) Describe three ways charges can be transferred from one object to another.
Charges can be transferred through direct contact, friction, or induction.
5.) What does it mean to make an object polar?
To make an object polar means the charges have been separated.
6.) Is the polarized object charged? Why or why not?
Yes the polarized object is not charged because it doesn't have an uneven number of charges.
7.) How does plastic wrap get a charge?
Plastic wrap gets a charge through friction when it is unrolled.
8.) What is Coulomb's Law?
Coulomb's Law is F= Kq1q2/d^2
9.) What does the q stand for in Coulomb's Law?
The "q" stands for the charge.
10.) A current-carrying wire is positively, negatively, or neutrally charged?
The wire is neutral.
Examples and Practice Problems
Why does your hair stick up when putting on a sweater or taking off a winter hat?
The hat steals electrons through friction. The hat then becomes negatively charged through friction while the hair becomes positively charged. Since like charges repel, the strands of hair stand up in an effort to get away from one another.
Explain the physics behind lightening and why lightening rods protect structures.
Clouds steal electrons and become negatively charged through friction. This induces positive charges in the ground structures. Since opposite charges attract, the positive and negative charges will move towards each other. Should the path be completed, the energy will come up through the ground and be released in the form of light, heat, or sound ( AKA Lightning and Thunder). Now lightning rods are pointy and charges are attracted to pointy things. If the lightning should strike the rod and the path to the ground be completed, then the lighting would get rerouted to the ground and the lightning would be less likely to strike the house, thus the house is protected.
Why does the plastic wrap stick to the ceramic bowl, but not a metal bowl?
The plastic wrap, when unrolled, becomes charged through friction. When brought near the bowl, the bowl polarizes. The positive charges in the bowl move close to the plactice wrap and the negative charges move away from the plastic wrap. The distance between the opposite attractive charges is smaller than the distance between the like repelling charges. According to Coulomb's Law " The force between any two charges is inversely proportional to the distance." F= kq1q2/d^2. since there is a greater distance between the repulsive forces the force between them will be less than the close attractive forces, this the plastic wrap sticks to the bowl. Now is won't stick to a metal bowl because metal is a conductor so when the plastic wrap comes near the metal bowl, all of the negative charges go into the ground, taking away all of the charges that would be attracted to the plastic wrap, leaving only the positive, thus no stick.
Why do clothes stick in the drier?
Cloths stick in the dryer because through friction the clothes are losing electrons become negatively charged and gaining electrons becoming positively charged. Since opposite charges attract, the clothes will be stuck together in the drier.
a.) If two positive charges are pushed closer together, how does the force between them change?b.) what formula guides your answer? c.) What happened to the stored energy in their electric field when this happens? Is this an attractive fore or a repulsive force?
a.) The force between them increases.
b.) F= kq1q2/d^2
c.) The energy increases, the like charges repel.
Part two: Electric Fields
1.) What is an electric field?
An electric field is the area of influence around a charge.
2.) What happens to the strength of an electric field as you move away from the charged article? How does the field lines show this?
The strength of the field decreases. The lines move farther apart from each other.
3.) What does the direction of the field lines show?
They show the direction in which the positive charges will be pushed.
Examples and Practice Problems
Why are electronics placed in metal boxes? Explain your answer
Metal boxes act as electric shields. The electric field inside all electric shields is zero which means the charges in the metal box will be pushed or pulled by outside electric charges. Metals allow the charges to distribute evenly and they are always moving therefore everything in the box will be pulled in one direction, but will have equal and opposite forces in the other direction.
When two like charges are pushed together closer and closer, what happens to the energy between them?
The energy between them increases.
When two oppositely charged objects are held close together (but NOT touching) and more of the opposite charges are added to each side, what happens to the energy between the two objects?
The energy increases.
Part three: Electric Potential/Electric Potential difference, Capacitors
1.) What is electric potential?
It is the electric potential energy/charge
2.) What is the formula for electric potential?
The formula is Electric potential= PE/q
3.) What is the common name for electric potential?
The common name is volts.
4.) What is electric potential measured in?
It is measured in volts.
5.) What is the difference between electric potential and electric potential energy?
Electric potential energy is the stored energy between the electric charges in the electric fields. Now Electric potential is the potential energy per charge.
6.) What specifically about electric potential is important to cause current?
The difference in electric potential
Examples and Practice Problems
1.) A flash is an example of a capacitor. Explain why you can't use your flash continuously and by doing so explain how capacitors work.
Flashes are capacitors, which are made up of two oppositely charged plates, not connected. Charges are then added to each side, which increases the force between them because of Coulomb's Law " F=kq1q2/d^2." The increase in force also causes the energy of the electric field to increase. So when they are connected for a brief second though a connecting wire, the energy goes rushing from one plate to the other and is released in the form of light and heat (i.e the flash). So there is no more energy available to be released as light and heat and it takes time for the charge + electric field's energy to increase. Therefore, it cannot work continuously.
2.) Show how something can have a higher voltage but not be as dangerous as something with a lower voltage.
High voltage Low Voltage
V= PE/q V=PE/q
(1000)= (10000)/ (10) (200)= (20,000)/ (100) <---- higher energy, more energy
(1000)= (1000) (200)= (200)
1000 vs. 200
Part four: Ohm's Law and Electric Potential Difference
1.) What is Ohm's Law?
Ohm's Law is I= V/R.
2.) What is the relationship between current and voltage? What are the definitions? What are they measured in? What are the symbols?
Voltage and current are directly proportional. Current is the energy moving through the wire carried by charges. Voltage is the measure in electric potential difference and causes current. Current is measured in Amps while voltage is measured in volts. The symbol for current is "I." The symbol for voltage is v.
3.) What is the relationship between current and resistance?
Current is inversely proportional to resistance.
4.) What is the difference between volt and voltage?
A volt is the electric potential potential difference. While voltage is the measure of the electric potential difference and causes current.
5.) What is the difference between current and voltage?
Current is the energy carried by charges moving through a wire while voltage is the measure in electric potential difference and causes current.
6.) What are some factors that affect the amount of resistance a wire could have?
The factors are temperature, size (wide, thick, long, thin), and type of metal.
7.) How will increasing these factors affect the resistance of that wire?
Temperature increase= Increase in resistance
Temperature decrease= Decrease in resistance
Width- wider= lower resistance
- narrow= higher resistance
Length- longer= increase resistance
Examples and Practice Problems
1.) In terms of voltage and current, why do flashlights get dimmer as the battery is exhausted? In your explanation be sure to explain the relationship you observed regarding the brightness and current as well as the relationship between voltage and current.
As a flashlight is being used, the voltage is converted into light and heat. In turn, the voltage is decreased which causes the current to decrease because they are directly proportional. The decrease in current causes the light to dim. Therefore, as the battery is exhausted, the flashlight is dimmer.
2.) In terms of resistance and current, why are some bulbs brighter than others when installed? In your explanation be sure to include the relationship between resistance and current as well as the relationship between brightness and current.
Some bulbs are brighter because they have a smaller resistance, since resistance and current are inversely proportional, the smaller the resistance the greater the current. Since current and brightness are dirtily related, the greater the current the brighter the bulb will be. Wow, science is cool!
3.) Why does a flashlight get dimmer as the battery becomes weaker?
The energy is converted to light and heat. In turn, the voltage decreased which causes the current to decrease since they are directly proportional. The decrease in current means there isn't as much energy flowing through which causes the light to be dimmer.
4.) Why do birds not get harmed if they stand on a wire, but would get harmed if one ran into both power line wires with its wings?
One power line doesn't have a difference in v from one side to the other. Therefore the circuit isn't complete, so there will be no difference in v, so no current is flowing, so no cooked bird. While if the birds were to touch both lines with its wings then the circuit would be complete and there would be a difference in v from one side to the other causing a current to flow through the bird. Current flowing= electrified bird. Thus the bird is harmed.
5.) A lightbulb filament starts out cold then gets warmer. What do you think happens to the current in the light bulb as the filament is heating up? Why?
As it gets warmer the resistance increases and since the resistance and current are inversely proportional we know that the current would go down.
6.) Why does connecting a dead battery with jumper cables to a working one with the car running make the battery work and why are the wires so thick?
Connecting the dead battery to a working one with jumper cables creates a complete circuit which causes a difference in v which causes current to flow. The energy of the current flows through the dead battery (storing energy in the battery) which creates a difference in electric potential causing current to flow making the car run. The wires are so thick because the thicker the cable, the lower the resistance will be. Since resistance and current are inversely proportional the lower the resistance is the greater the current will be, the more current there is, the more energy will flow meaning the battery will work sooner due to more energy stored in a shorter period of time.
7.) Why is it dangerous to plug american appliances into european circuits?
The american appliances have a low resistance meaning they have a high current. They also have a high voltage meaning they have a high current as well. When the american appliance is plugged in a circuit that has a higher v than it is designed for, it'll have a greater difference in v which will cause more current to flow and a high current flowing through a low resistance appliance because they are inversely proportional, will overload the appliance ands cause it to catch on fire.
8.) Why do lightbulbs typically burn out when they are immediately turned on?
The light bulbs typically burn out when there are immediately turned on because the bulb is cold and cold= low resistance. Since current and resistance are inversely proportional the current would be high and a high current would break the old filament while a bulb that's been on a while will be hot= high resistance. This means there would be a low current. A low current means no broken filament.
9.) How does the current in the circuit compare before the light bulb and after?
The current throughout the circuit is the same all throughout it.
Part five: Types of current, source of Electrons, Power
1.) What are the two types of current?
The two types of current are alternating (AC) and direct (DC).
2.) How does each one move?
The electrons in direct current only move in one direction. The electrons in alternating current move in one direction and then the opposite.
3.)What causes electric shock?
Electric shock= current moving in your body.
4.) How many electrons do you get from the wall during electric shock?
None because electrons originate in your body.
5.) What is the formula for power, for this unit?
The formula is P= IV or Power= Current x Voltage
6.) What actually carries the energy through the wire?
The electrons are moving and they are carrying the current that carries energy in the wire.
Part six: Parallel and Series Circuits
1.) What is a fuse and what function does is serve?
A fuse is "a safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level."
2.) What is the difference between the working and the broken fuse?
A working fuse completes the circuit and conducts current while the broken fuse doesn't complete the circuit or conduct current.
3.) Are houses wired with parallel or series circuits?
Houses are wired with parallel circuits.
4.) What happens to the total resistance as more appliances are added to a series? To a parallel?
The resistance in a series increases . The resistance in a parallel decreases.
5.) What happens to the current as more appliances are added to a series? To a parallel?
The current decreases in a series. The current increases in a parallel.
6.) What happens to the brightness (or power output) as more appliances are added to a series? To a parallel?
The brightness decreases in a series. The brightness stays the same in a parallel.
7.) What happens to the other lightbulbs when one is removed or stops working in a series? In a parallel?
In a series, they all shut off. In a parallel, nothing happens.
Practice Problem
1.) How does a fuse/circuit breaker protect your house? In your answer discuss how the various outlets in your home are wired. Why is a fuse needed? How is a fuse wired? How does a fuse work?
A fuse is added only to a parallel circuit, but it is wired in a series compared to that circuit. The fuse will break if too much current is drawn from the wall. This will cut the current to all devices to prevent fires because too much current is out.
2.) Why is there no effect on the other branches in a parallel circuit when one branch of the circuit is opened of closed?
This is because they are still connected to an electric circuit, so there is still an electric potential difference.
3.) Are automobile lights wired in a parallel or a series?
They are wired in a parallel.
4.) Your electronics friend needs a 20 ohm resistor, but only has 40 ohm resistors. How can he combine them to produce to an equivalent resistance of 10 ohms?
They are wired in a parallel. You add 2 resistors.
5.) How does the brightness of identical light bulbs compare? (see picture below)
- A + B are dimmer than C
b.) Which lightbulb draws more current?
Lightbulb C draws more current.
c.) What will happen to B and C if A is unscrewed?
If A is unscrewed, B= off and C= no change.
1.) Charges and Polarization including Coulomb's Law
2.) Electric Fields
3.) Electric Potential/Electric Potential difference, Capacitors
4.) Ohm's Law and Electric Potential difference
5.) Types of current, source of Electrons, Power
6.) Parallel and Series Circuits
Part one: Charges and Polarization including Coulomb's Law
1.) What are the two types of charges?
The two types of charges are positive and negative.
2.) How does something become positive, negative, and neutral?
To become protons lose electrons. To become negative they lose electrons. To become neutral there is a balance of positive and negative charges.
3.) What do like charges do? What do unlike charges do?
The like charges repel while the opposite charges are attracted to each other.
4.) Describe three ways charges can be transferred from one object to another.
Charges can be transferred through direct contact, friction, or induction.
5.) What does it mean to make an object polar?
To make an object polar means the charges have been separated.
6.) Is the polarized object charged? Why or why not?
Yes the polarized object is not charged because it doesn't have an uneven number of charges.
7.) How does plastic wrap get a charge?
Plastic wrap gets a charge through friction when it is unrolled.
8.) What is Coulomb's Law?
Coulomb's Law is F= Kq1q2/d^2
9.) What does the q stand for in Coulomb's Law?
The "q" stands for the charge.
10.) A current-carrying wire is positively, negatively, or neutrally charged?
The wire is neutral.
Examples and Practice Problems
Why does your hair stick up when putting on a sweater or taking off a winter hat?
The hat steals electrons through friction. The hat then becomes negatively charged through friction while the hair becomes positively charged. Since like charges repel, the strands of hair stand up in an effort to get away from one another.
Explain the physics behind lightening and why lightening rods protect structures.
Clouds steal electrons and become negatively charged through friction. This induces positive charges in the ground structures. Since opposite charges attract, the positive and negative charges will move towards each other. Should the path be completed, the energy will come up through the ground and be released in the form of light, heat, or sound ( AKA Lightning and Thunder). Now lightning rods are pointy and charges are attracted to pointy things. If the lightning should strike the rod and the path to the ground be completed, then the lighting would get rerouted to the ground and the lightning would be less likely to strike the house, thus the house is protected.
Why does the plastic wrap stick to the ceramic bowl, but not a metal bowl?
The plastic wrap, when unrolled, becomes charged through friction. When brought near the bowl, the bowl polarizes. The positive charges in the bowl move close to the plactice wrap and the negative charges move away from the plastic wrap. The distance between the opposite attractive charges is smaller than the distance between the like repelling charges. According to Coulomb's Law " The force between any two charges is inversely proportional to the distance." F= kq1q2/d^2. since there is a greater distance between the repulsive forces the force between them will be less than the close attractive forces, this the plastic wrap sticks to the bowl. Now is won't stick to a metal bowl because metal is a conductor so when the plastic wrap comes near the metal bowl, all of the negative charges go into the ground, taking away all of the charges that would be attracted to the plastic wrap, leaving only the positive, thus no stick.
Why do clothes stick in the drier?
Cloths stick in the dryer because through friction the clothes are losing electrons become negatively charged and gaining electrons becoming positively charged. Since opposite charges attract, the clothes will be stuck together in the drier.
a.) If two positive charges are pushed closer together, how does the force between them change?b.) what formula guides your answer? c.) What happened to the stored energy in their electric field when this happens? Is this an attractive fore or a repulsive force?
a.) The force between them increases.
b.) F= kq1q2/d^2
c.) The energy increases, the like charges repel.
Part two: Electric Fields
1.) What is an electric field?
An electric field is the area of influence around a charge.
2.) What happens to the strength of an electric field as you move away from the charged article? How does the field lines show this?
The strength of the field decreases. The lines move farther apart from each other.
3.) What does the direction of the field lines show?
They show the direction in which the positive charges will be pushed.
Examples and Practice Problems
Why are electronics placed in metal boxes? Explain your answer
Metal boxes act as electric shields. The electric field inside all electric shields is zero which means the charges in the metal box will be pushed or pulled by outside electric charges. Metals allow the charges to distribute evenly and they are always moving therefore everything in the box will be pulled in one direction, but will have equal and opposite forces in the other direction.
When two like charges are pushed together closer and closer, what happens to the energy between them?
The energy between them increases.
When two oppositely charged objects are held close together (but NOT touching) and more of the opposite charges are added to each side, what happens to the energy between the two objects?
The energy increases.
Part three: Electric Potential/Electric Potential difference, Capacitors
1.) What is electric potential?
It is the electric potential energy/charge
2.) What is the formula for electric potential?
The formula is Electric potential= PE/q
3.) What is the common name for electric potential?
The common name is volts.
4.) What is electric potential measured in?
It is measured in volts.
5.) What is the difference between electric potential and electric potential energy?
Electric potential energy is the stored energy between the electric charges in the electric fields. Now Electric potential is the potential energy per charge.
6.) What specifically about electric potential is important to cause current?
The difference in electric potential
Examples and Practice Problems
1.) A flash is an example of a capacitor. Explain why you can't use your flash continuously and by doing so explain how capacitors work.
Flashes are capacitors, which are made up of two oppositely charged plates, not connected. Charges are then added to each side, which increases the force between them because of Coulomb's Law " F=kq1q2/d^2." The increase in force also causes the energy of the electric field to increase. So when they are connected for a brief second though a connecting wire, the energy goes rushing from one plate to the other and is released in the form of light and heat (i.e the flash). So there is no more energy available to be released as light and heat and it takes time for the charge + electric field's energy to increase. Therefore, it cannot work continuously.
2.) Show how something can have a higher voltage but not be as dangerous as something with a lower voltage.
High voltage Low Voltage
V= PE/q V=PE/q
(1000)= (10000)/ (10) (200)= (20,000)/ (100) <---- higher energy, more energy
(1000)= (1000) (200)= (200)
1000 vs. 200
Part four: Ohm's Law and Electric Potential Difference
1.) What is Ohm's Law?
Ohm's Law is I= V/R.
2.) What is the relationship between current and voltage? What are the definitions? What are they measured in? What are the symbols?
Voltage and current are directly proportional. Current is the energy moving through the wire carried by charges. Voltage is the measure in electric potential difference and causes current. Current is measured in Amps while voltage is measured in volts. The symbol for current is "I." The symbol for voltage is v.
3.) What is the relationship between current and resistance?
Current is inversely proportional to resistance.
4.) What is the difference between volt and voltage?
A volt is the electric potential potential difference. While voltage is the measure of the electric potential difference and causes current.
5.) What is the difference between current and voltage?
Current is the energy carried by charges moving through a wire while voltage is the measure in electric potential difference and causes current.
6.) What are some factors that affect the amount of resistance a wire could have?
The factors are temperature, size (wide, thick, long, thin), and type of metal.
7.) How will increasing these factors affect the resistance of that wire?
Temperature increase= Increase in resistance
Temperature decrease= Decrease in resistance
Width- wider= lower resistance
- narrow= higher resistance
Length- longer= increase resistance
Examples and Practice Problems
1.) In terms of voltage and current, why do flashlights get dimmer as the battery is exhausted? In your explanation be sure to explain the relationship you observed regarding the brightness and current as well as the relationship between voltage and current.
As a flashlight is being used, the voltage is converted into light and heat. In turn, the voltage is decreased which causes the current to decrease because they are directly proportional. The decrease in current causes the light to dim. Therefore, as the battery is exhausted, the flashlight is dimmer.
2.) In terms of resistance and current, why are some bulbs brighter than others when installed? In your explanation be sure to include the relationship between resistance and current as well as the relationship between brightness and current.
Some bulbs are brighter because they have a smaller resistance, since resistance and current are inversely proportional, the smaller the resistance the greater the current. Since current and brightness are dirtily related, the greater the current the brighter the bulb will be. Wow, science is cool!
3.) Why does a flashlight get dimmer as the battery becomes weaker?
The energy is converted to light and heat. In turn, the voltage decreased which causes the current to decrease since they are directly proportional. The decrease in current means there isn't as much energy flowing through which causes the light to be dimmer.
4.) Why do birds not get harmed if they stand on a wire, but would get harmed if one ran into both power line wires with its wings?
One power line doesn't have a difference in v from one side to the other. Therefore the circuit isn't complete, so there will be no difference in v, so no current is flowing, so no cooked bird. While if the birds were to touch both lines with its wings then the circuit would be complete and there would be a difference in v from one side to the other causing a current to flow through the bird. Current flowing= electrified bird. Thus the bird is harmed.
5.) A lightbulb filament starts out cold then gets warmer. What do you think happens to the current in the light bulb as the filament is heating up? Why?
As it gets warmer the resistance increases and since the resistance and current are inversely proportional we know that the current would go down.
6.) Why does connecting a dead battery with jumper cables to a working one with the car running make the battery work and why are the wires so thick?
Connecting the dead battery to a working one with jumper cables creates a complete circuit which causes a difference in v which causes current to flow. The energy of the current flows through the dead battery (storing energy in the battery) which creates a difference in electric potential causing current to flow making the car run. The wires are so thick because the thicker the cable, the lower the resistance will be. Since resistance and current are inversely proportional the lower the resistance is the greater the current will be, the more current there is, the more energy will flow meaning the battery will work sooner due to more energy stored in a shorter period of time.
7.) Why is it dangerous to plug american appliances into european circuits?
The american appliances have a low resistance meaning they have a high current. They also have a high voltage meaning they have a high current as well. When the american appliance is plugged in a circuit that has a higher v than it is designed for, it'll have a greater difference in v which will cause more current to flow and a high current flowing through a low resistance appliance because they are inversely proportional, will overload the appliance ands cause it to catch on fire.
8.) Why do lightbulbs typically burn out when they are immediately turned on?
The light bulbs typically burn out when there are immediately turned on because the bulb is cold and cold= low resistance. Since current and resistance are inversely proportional the current would be high and a high current would break the old filament while a bulb that's been on a while will be hot= high resistance. This means there would be a low current. A low current means no broken filament.
9.) How does the current in the circuit compare before the light bulb and after?
The current throughout the circuit is the same all throughout it.
Part five: Types of current, source of Electrons, Power
1.) What are the two types of current?
The two types of current are alternating (AC) and direct (DC).
2.) How does each one move?
The electrons in direct current only move in one direction. The electrons in alternating current move in one direction and then the opposite.
3.)What causes electric shock?
Electric shock= current moving in your body.
4.) How many electrons do you get from the wall during electric shock?
None because electrons originate in your body.
5.) What is the formula for power, for this unit?
The formula is P= IV or Power= Current x Voltage
6.) What actually carries the energy through the wire?
The electrons are moving and they are carrying the current that carries energy in the wire.
Part six: Parallel and Series Circuits
1.) What is a fuse and what function does is serve?
A fuse is "a safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level."
2.) What is the difference between the working and the broken fuse?
A working fuse completes the circuit and conducts current while the broken fuse doesn't complete the circuit or conduct current.
3.) Are houses wired with parallel or series circuits?
Houses are wired with parallel circuits.
4.) What happens to the total resistance as more appliances are added to a series? To a parallel?
The resistance in a series increases . The resistance in a parallel decreases.
5.) What happens to the current as more appliances are added to a series? To a parallel?
The current decreases in a series. The current increases in a parallel.
6.) What happens to the brightness (or power output) as more appliances are added to a series? To a parallel?
The brightness decreases in a series. The brightness stays the same in a parallel.
7.) What happens to the other lightbulbs when one is removed or stops working in a series? In a parallel?
In a series, they all shut off. In a parallel, nothing happens.
Practice Problem
1.) How does a fuse/circuit breaker protect your house? In your answer discuss how the various outlets in your home are wired. Why is a fuse needed? How is a fuse wired? How does a fuse work?
A fuse is added only to a parallel circuit, but it is wired in a series compared to that circuit. The fuse will break if too much current is drawn from the wall. This will cut the current to all devices to prevent fires because too much current is out.
2.) Why is there no effect on the other branches in a parallel circuit when one branch of the circuit is opened of closed?
This is because they are still connected to an electric circuit, so there is still an electric potential difference.
3.) Are automobile lights wired in a parallel or a series?
They are wired in a parallel.
4.) Your electronics friend needs a 20 ohm resistor, but only has 40 ohm resistors. How can he combine them to produce to an equivalent resistance of 10 ohms?
They are wired in a parallel. You add 2 resistors.
5.) How does the brightness of identical light bulbs compare? (see picture below)
- A + B are dimmer than C
b.) Which lightbulb draws more current?
Lightbulb C draws more current.
c.) What will happen to B and C if A is unscrewed?
If A is unscrewed, B= off and C= no change.
6.) Consider the three parts of the circuit, A, the top branch with two bulbs, B, the middle branch with one bulb, and C, the battery.
a.) rank the current through each from the greatest to the least.
C, B, A
b.) Rank the voltage across each from the greatest to the least.
Anything in a parallel circuit has the same voltage.
Subscribe to:
Posts (Atom)