Resistance
Resistance
The friction of a car’s tires against the road is an example of resistance. The flow of water through a pipe is also an example of resistance. The water is slowed down by the sides of the pipe, causing it to move more slowly through the pipe
ResistanceResistance is a property of matter that slows movement.
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Resistance between
the tire and the road
gives “grip”.
What happens
when there is no
resistance?
The friction of a car’s tires against the road is an example of resistance. The flow of water through a pipe is also an example of resistance. The water is slowed down by the sides of the pipe, causing it to move more slowly through the pipe
ResistanceResistance is a property of matter that slows movement.
Resistance between
the tire and the road
gives “grip”.
What happens
when there is no
resistance?
Resistance can be very important!
The friction of a car’s tires against the road is an example of resistance. The flow of water through a pipe is also an example of resistance. The water is slowed down by the sides of the pipe, causing it to move more slowly through the pipe
The friction of a car’s tires against the road is an example of resistance. The flow of water through a hose is also an example of resistance. The water is slowed down by the sides of the hose, causing it to move more slowly through the hose.
The friction of a car’s tires against the road is an example of resistance. The flow of water through a hose is also an example of resistance. The water is slowed down by the sides of the hose, causing it to move more slowly through the hose.
ResistanceResistance is a property of matter that slows movement.
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Electrons flowing through a wire or a load (like a light bulb) also experience resistance. This resistance reduces the electrical energy of the circuit, converting some of the energy into some other form.
The friction of a car’s tires against the road is an example of resistance. The flow of water through a hose is also an example of resistance. The water is slowed down by the sides of the hose, causing it to move more slowly through the hose.
Resistance is a property of matter that slows movement.
Resistance
The wire and lamp resist
the movement of electrons.
Electrons flowing through a wire or a load (like a light bulb) also experience resistance. This resistance reduces the electrical energy of the circuit, converting some of the energy into some other form.
The friction of a car’s tires against the road is an example of resistance. The flow of water through a hose is also an example of resistance. The water is slowed down by the sides of the hose, causing it to move more slowly through the hose.
Resistance is a property of matter that slows movement.
Resistance
Electron movement
Resistance
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Resistance
The friction of a car’s tires against the road is an example of resistance. The flow of water through a hose is also an example of resistance. The water is slowed down by the sides of the hose, causing it to move more slowly through the hose.
Resistance is a property of matter that slows movement.
Electrons flowing through a wire or a load (like a light bulb) also experience resistance. This resistance reduces the electrical energy of the circuit, converting some of the energy into another form.
Heat
Light
Sound
Named in honor of Georg Simon Ohm
(1787-1854)
Resistance
The unit used to measure resistance is the ohm (!). The mathematical relationship between voltage, current and resistance is called Ohm’s Law.The unit used to measure resistance is the ohm (!). The mathematical relationship between voltage, current and resistance is called Ohm’s Law.
Electrical Resistance
Electrical resistance is the ability of a material to oppose the flow of electric current. Symbol is “R”
The greater the resistance the lower the current, and the warmer the material comes when current flow through it.
Internal resistance depends on many factors. (we will look at 4)
1. Type of Material
Some materials conduct electricity well and electrons can move within the material freely.
For example copper is an excellent conducto r and has low e lect r ica l resistance.
2. Cross-Sectional Area
the diameter of the cross section gives you a sense of how thick the wire is. Thicker wires have less internal resistance than thinner ones.
Electrons flowing through thicker wire have more room to move freely.
3. Length
As you increase the length of the wire, its internal resistance increases. This happens because electrons have to travel through more material.
4. Temperature
When a wire gets warmer, the atoms that make up the wire gain energy and vibrate faster.
Increased vibrations cause more collisions, so resistance increases with temperature.
Resistors in Circuits
A resistor ~ is a device in an electrical circuit that reduces the flow of electric current.
Examples: a lamp that has multiple brightness settings or a dimmer switch
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