1.
Copy and complete this table:
Potential
difference 
Current 
Resistance 
10V 
5A 

12V 
3A 

Mains 
10A 

20kV 
50A 

10V 

100ohms 
9V 

10Kohms 

1.8mA 
2.2kohms 
2.
If a resistor has a resistance of 200ohms calculate the voltage required
to cause a current of 100mA to flow
3.
Repeat for a resistance of 200lohms and a current of 20Amperes
4.
A
300kohm resistor has 1A flowing through it.
What is the p.d. across it?
5.
(a) Write down the current flowing through R_{1}
(b) Calculate the resistance of R_{1 }
(c) Calculate the p.d. across R_{2 }
(d) Calculate the resistance of R_{2 }
(e)
Write down all the scientific principles that this question relies upon.
6.
What is the power of an appliance that passes 200J of energy in 4 seconds
7.
What is the power of an electric iron that passes 600kJ in 14 minutes?
8.
What is the power of an electric kettle that uses mains electricity
passes a current of 3A?
9.
A fluorescent light bulb passes a current of 150mA when connected to the
mains. What is its power rating?
10.
What is the current passed through a colour tv rated at 340W that is
connected to the mains?
11.
Why would it be wrong to use a 5A fuse in an immersion heater rated at
3000W (connected to the mains)?
12.
Why would it be wrong to use a 13A fuse in a table lamp rated at 60W when
connected to the mains supply?
13. A 3kW electric fire is used for 10 minutes. (a) Calculate the Joules of electricity that it converts. (b) What energy is the electricity converted into?
**
14. What is the
resistance of a mains powered electric fire rated at 1kW?
**
15. An electric light
bulb, rated at 100W, has a resistance of 26 ohms.
Calculate the voltage of the power supply.
16.
A dishwasher has a resistance of 19 ohms.
Calculate the energy converted by the dishwasher during a half hour cycle
if used at mains voltage?
17.
Calculate the kWhours of electricity consumed by a 2kW electric fire in 2
hours.
18.
If 1 unit of electricity costs 7p (1kWhr = 7p) calculate the cost of
using an immersion heater rated at 4000W for 10hours.
**
19. Calculate the
resistance of an electric kettle if it costs 16.8p per hour to run it on mains
power. (Take 1 unit = 7p)
20. An office has five 60W bulbs, a 2kW electric fire and a 200W computer. Calculate the maximum electricity costs of this office per 24 hours period. (Take 1 unit = 7p)