Ch9 Energy and Power

Question 1

what is EMF

Answer 1

EMF is the energy transferred from other forms to electric per unit charge.
emf = W/Q

Question 2

what is potential difference?

Answer 2

p.d. is the energy transferred from electrical to other forms per unit charge
V= W/Q

Question 3

ohms law.

Answer 3

• The current through a conductor is directly proportional to the p.d. across it, when temperature is constant.

Question 4

ohms law experiment

Answer 4

a circuit consist of :
- ammeter.
- conductor.
- voltameter across the conductor.
- variable resistance.
vary the variable resistance to vary the p.d. across the conductor.
measure p.d. and I
plot a graph of V across I.
if the graph is straight through the origin V is proportional to I

Question 5

what is kWh

Answer 5

kWh = Pt
kW is a measure of power
h is a measure of time
Pt = W
1kWh is the amount of energy transferred by 1KW device in 1 hour