Electrical energy, power and domestic wiring

Question 1 of 10

Energy-saving bulbs (LEDs and CFLs) are preferred because they

Question 2 of 10

The power of an appliance is the energy it converts per second.

Question 3 of 10

A 100 W bulb uses 1 kWh of energy in 10 hours.

Question 4 of 10

In the standard colour code, the neutral wire is

Question 5 of 10

A 500 W heater is used for 3 hours a day for 20 days. At GH₵1.20 per kWh, find the cost.

Question 6 of 10

Draw and label a three-pin plug and explain the function of each wire and of the fuse.

Question 7 of 10

Find the power dissipated in a 48 Ω resistor connected across 12 V.

Question 8 of 10

Show that P = I²R and P = V²/R, starting from P = IV. A 240 V, 1,200 W iron is used. Find (a) the current, (b) its resistance, (c) the energy used in 15 minutes.

Question 9 of 10

Explain why appliances in a house are connected in parallel rather than in series. Give three reasons.

Question 10 of 10

The earth wire protects the user by