2.2 Resistance

Question 1

What is Potential Difference?

Answer 1

The pd between two points is the energy converted from electrical potential energy to some other form per coulomb of charge flowing from one point to the other

Unit = V [ JC^-1 ]

Question 2

What is ohm’s law?

Answer 2

The current in a metal wire at constant temperature is proportional to the pd across it

Question 3

What is electrical resistance?

Answer 3

The resistance of a conductor is the pd (V) placed across it divided by the resulting current (I) through it.
R = V/I
Unit = Ω

Question 4

What is resistivity?

Answer 4

The resistance, R, of a metal wire of length L and cross-sectional area A is given by R=pL/A, in which p, the resistivity, is a constant (at constant temperature) for the material of the wire

unit = Ωm

Question 5

What is superconducting transition temperature?

Answer 5

The temperature at which a material, when cooled, loses all its electrical resistance, and becomes super-conducting. Some materials (e.g. copper) never become superconducting however low the temperature becomes.