Electric Current and Charge

Question 1

Behaviour of electrons in a solid with no applied voltage.

Answer 1

‘Free’ electrons have a random thermal speed around 1x10⁶ms^-1. Random movement so no current

Question 2

Electrons in a region of potential difference

Answer 2

Accelerate towards a region of positive potential, gaining K.E.

Question 3

Collisions of electrons

Answer 3

Electrons collide with vibrating atoms reducing electron speed and increasing internal energy in the metal (observed as a rise in temperature).

Question 4

Electrical resistance

Answer 4

Explained by collisions between free electrons and atoms

Question 5

Electron drift

Answer 5

There is a drift of negative charge towards the region of positive potential. This constitutes an electric current in a metal

Question 6

Current

Answer 6

Conventional current: flows from an area of positive potential to an area of lower potential

In metals, current is due to the motion of electrons in the opposite direction.

Question 7

Definition of current

Answer 7

The amount of electric charge passing a fixed point in 1 second

Question 8

Ampere

Answer 8

1A is a charge of 1C passing a fixed point in a circuit every second