7.2 Current and potential difference

Question 1

What is current?

Answer 1

Current - the rate of flow of charge

= how many charged particles pass a point every second (e.g. rate of flow of electrons in a metal)

Question 2

What is the unit of current?

Answer 2

Amperes (Amps, A)

Question 3

What is the unit of charge?

Answer 3

Coulombs (C)

Question 4

What equation relates charge, current and time?

Answer 4

Q = I x t

Q = charge (coulombs)
I = current (amperes)
t = time (seconds)

Question 5

What is voltage?

Answer 5

Voltage (or “potential difference” is the driving force that pushes charge around

Voltage = the energy transferred per unit charge passed (i.e. how much energy each coulomb of chrage transfers as it passes between two points in a circuit)

Question 6

What is the unit of potential difference?

Answer 6

Volts (V)

1 volt = 1 joule per coulomb

Question 7

Write the equation relating energy, charge and potential difference

Answer 7

E = Q x V

E = energy transferred (in joules, J)

Q = charge (coulombs. C)

V = potential difference (volts, V)