 A
lamp has a p.d. of 12 V across it. Calculate how much electrical
energy is transferred when:

A charge of 400 C
passes through it;

A current of 2.5 A
passes through it for 30
s
 A
230 V electric heater takes a current of 2.0 A. Calculate the heat
produced if it is switched on for 5.0
minutes.

Calculate the p.d. across a wire if the energy transferred is:

600 J when a charge
of 50 C passes through it;

450 J when there is
a steady current of 0.5 A flowing for 20 s.
 A
230 V kettle transfers 6.9 × 10^{5} Joules of energy in 5.0
minutes. What is the current in the kettle?


What is the p.d.
across a wire of resistance 8.0
W
when there is a current of 1.5 A flowing through it?

What is the
resistance of a wire if a potential difference. of 6.0 V drives
a current of 0.25 A through it?

A p.d. of 3.0 V is
applied across a wire of resistance 15
W.
What is the current in the
wire?


The resistivity of
copper is 1.7 × 10^{8}
Wm.
Calculate the resistance of 50 m of copper cable with a
crosssectional area of 2.5 × 10^{6} m.

What is the voltage
drop across this cable if it carries a current of
13amps?

The resistivity of nichrome is 1.1 × 10^{6}
Wm.
Calculate the lengths of 0.4 mm diameter nichrome wire needed to
make coils of resistance:

2.0
W;

5.0
W
