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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