7/30/2019 Sc PMR

1/1

COST OF ELECTRICAL ENERGY USAGE

1. A kettle with power and voltage ratingsof 1000 W and 240 V is used to boil some water.

If the water starts to boil in 10 minutes, calculate

the amount of electrical energy used.

2. An air-conditioner which has power and

voltage ratings of 1.5 kW and 230 V, is switched

on every day for 8 hours. Find the amount of

electrical energy used in the month of June.

3. An immersion heater rated at 600 W240 V is used to boil a jud of water. If it uses

252 kJ of electrical energy, how long does it take

to boil the water?

4. An electrical kettle rated at 1.5 kW 240

V is used for 10 minutes each day. If the

appliance is used for 30 days and that one unit ofelectricity costs 20 sen, find the total cost ofelectrical energy used.

5. Rahimah uses an electric iron with a

rating of 1500 W, 240 V. She has to pay

RM1.50 each time she uses the iron. How long

is the iron used each time if one unit of electrical

energy costs RM0.20?

6.(a) The power label on the air conditioner

is 2.5 Kw, 240 V. What is the suitable

fuse rating for the air conditioner?

(b) Calculate the cost of using the air

conditioner for 8 hours per day for 1

week if the cost of each unit of

electrical energy is RM0.25.

7.

Electrical

appliance

Period

used

Energy Used

(kWh)

Air conditioner

(1200 W)

5.5 hours

Television

(950 W)

8 hours

Computer

(500 W)

6 hours

Rice cooker

(600 W)

30

minutes

8. The electricity tariff is as follows :

Calculate the cost of using an appliance

marked 600 W, 240 V for 10 hours per day

for 31 days.

9. An electrical appliance which has apower and voltage rating of 2.5 kW 240 V is

used in a house with a mains voltage of 230

V. The correct fuse to use is ____________

10. The power rating of a lamp is 60 W. If

the voltage across the lamp is 240 V,

calculate the current flowing through thelamp.

11. Your electric kettle has a voltage and power

rating of 220 V, 1000 W.(a) How much current will flow through

your electric kettle when it is switched

on ?

(b) If you are given four fuses with ratings2A, 5A, 10A and 13A, which one would

you choose for your electric kettle?

12. An electric toaster has a rating of 1000W, 240 V. What is the most suitable fuse

rating for this toaster?

13.

Calculate the cost of electrical energy used if

each unit of energy costs RM0.20.

The first 50 units is 15 sen per unit.

The next 100 units is 30 sen per unit.

Each additional unit is 40 sen per unit.

Power and voltage rating 1600 W, 240 VUsage per day - 5 hours

Number of days used - 30 days