Chapter 3.4 - 'Resistance'

Question 1

Define ‘resistance’.

Answer 1

A measure of how hard it is for current to flow through a particular material.

Measured in ohms. Ω

Question 2

State variables affecting resistance.

Answer 2

Length - Longer = more resistance

Thickness - Thicker = less resistance

Temperature - Higher temperature = more resistance
(More kinetic energy means the more likely an electron will collide with an ion as it moves past)

Question 3

State ‘Ohms law’.

Answer 3

V=IxR
R=V/I

Where V is the potential difference in volts (V)
I is the current in amps (A)
R is the constant of the proportionality called resistance, in ohms (Ω).

Question 4

State the difference between ‘Ohmic’ and ‘non Ohmic’ conductors.

Answer 4

The ratio of I/V will be constant for an ohmic conductor, whilst a non ohmic conductor will vary.

Or more simply, the conductor will have a constant resistance.