Electric cells

Question 1

Emf (ε) of a battery

Answer 1

Work done per unit charge in moving a charge from one terminal of a battery to the other in volts

Question 2

By conservation of energy , Emf is the same as work done moving charge q around the circuit. Express this as a formula

Answer 2

ε=W/q

Question 3

Relationship between emf and power (formula)

Answer 3

ε=P/I

Question 4

Internal resistance

Answer 4

resistance caused by materials making up cell

Question 5

Potential difference across a real battery

Answer 5

V = ε-Ir

Question 6

Potential difference across an ideal battery

Answer 6

ε

Question 7

On a voltage vs current graph, what does the gradient tell you?

Answer 7

Internal resistance(r)

V=ε-Ir
y=c-xm

Question 8

When does V=ε in a real battery?

Answer 8

When I=0

But with a current, V<ε

Question 9

What is a primary cell?

Answer 9

Primary cells cannot be recharged

E.g. Triple A batteries

Question 10

What is a secondary cell?

Answer 10

Secondary cells can be recharged

E.g. car battery