# Resistance and Resistivity Revision/Notes

This is more condensed than the OCR Physics 1 textbook. I have taken all the waffle out the book. Hope you find it helpful.

- Created by: Emily Rowe
- Created on: 20-11-13 18:16

First 189 words of the document:

Chapter 10 Resistance and

Resistivity

Electrical Resistance:

The size of a current is determined by two factors:

The potential difference of voltage V across the lamp the greater the voltage, the greater the

current for a given lamp.

The resistance R of the lamp the greater the resistance, the smaller the current for a given

voltage.

Meaning of electrical resistance:

To demonstrate that different lamps have different resistances we can connect and torch bulb and car

headlamp in series to a battery. The current is the same in each component, but the voltage across the

torch bulb will be greater than the voltage across the headlamp. The torch bulb has a larger resistance than

the headlamp.

The resistance of any component is defined as:

resistance = voltage

current

or

R=V

I

Defining the Ohm:

The unit of resistance, the ohm, can be determined from the equation that defines resistance:

resistance = voltage

current

The ohm is equivalent to `1 volt per ampere'. That is:

1 = 1V A-1

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