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FORM 3 SCIENCE 6.4

Total questions: 20

Worksheet time: 10mins

Name
Class
Date
1.

A toaster, rated 1500 W 240 V, is switched on for 15 minutes. Calculate the energy used.

a)

3600 J

b)

22 500 J

c)

216 000 J

d)

1 350 000 J

2.

An air-con, rated 1.8 kW 240 V, is switched on for 10 minutes. Calculate the energy used.

a)

1 080 000 J

b)

144 000 J

c)

2400 J

d)

18 J

3.

The electrical energy used by a fan for 4 minutes is 170 kJ. Calculate the power of this fan in W.

a)

42.5

b)

42500

c)

708

d)

0.708

4.

A television rated 1.2 kW , 240 V is connected to a 240V electricity supply. Calculate curent that flows through the television.

a)

5 A

b)

2.5 A

c)

0.005

d)

1.0 A

5.

An oven rated 750 W, 220 V is switched on for 45 minutes. Ho much electrical energy is used by the oven?

a)

3.4 J

b)

165000 J

c)

33750 J

d)

2025000 J

6.

An oven rated 750 W, 220 V is switched on for 45 minutes. Calculate the cost of energy that is used by the oven if the cost per 1 unit is 30 sen?

a)

3 sen

b)

17 sen

c)

16875 sen

d)

4 sen

7.

A 5kW electric cooker is used for 30 minutes to cook. Calculate the cost of electrical energy used if the rate per unit is 5 cents.

a)

RM 125

b)

RM 12

c)

RM 12.50

d)

RM125.50

8.

An electric heater is rated 230V, 10 A. Calculate the power of the electric heater in kW.

a)

2300

b)

23

c)

2.3

d)

0.23

9.

An oven rated 750 W, 220 V is switched on for 45 minutes. Calculate the cost of energy that is used by the oven if the cost per 1 unit is 30 sen?

a)

3 sen

b)

17 sen

c)

16875 sen

d)

4 sen

10.

The electrical energy used by a fan for 4 minutes is 170 kJ. Calculate the power of this fan in W.

a)

42.5

b)

42500

c)

708

d)

0.708

11.

A television rated 1.2 kW , 240 V is connected to a 240V electricity supply. Calculate curent that flows through the television.

a)

5 A

b)

2.5 A

c)

0.005

d)

1.0 A

12.

An oven rated 750 W, 220 V is switched on for 45 minutes. Calculate the cost of energy that is used by the oven if the cost per 1 unit is 30 sen?

a)

3 sen

b)

17 sen

c)

16875 sen

d)

4 sen

13.

A 5kW electric cooker is used for 55 minutes to cook. Calculate the cost of electrical energy used if the rate per unit is 50 sen.

a)

RM 0.23

b)

RM 230

c)

RM 2.30

d)

RM275

14.

Afiqah uses her laptop everyday in her office from morning till lunch hour. Hong long does she use the laptop in a day?

a)

4 hours

b)

6 hours

c)

8 hours

d)

10 hours

15.

How much does the electricity consumption need to be paid per month for Afiqah's laptop?

a)

RM 5.80

b)

RM 5.75

c)

RM 0.58

d)

RM 0.57

16.

An oven rated 750 W is switched on for 45 minutes. Calculate the cost of energy that is used by the oven if the cost per 1 unit is 25cents?

a)

RM12.94

b)

RM12.90

c)

RM 0.12

d)

RM2.90

17.

A device has 100J of input electrical energy supplied and only 75J of useful energy output. Calculate the energy efficiency of the device.

a)

85%

b)

75%

c)

65%

d)

55%

18.

Calculate the energy efficiency for an electric motor if the input electrical supplied is 400J and only 180J of useful energy output.

a)

0.45%

b)

0.44%

c)

44%

d)

45%

19.

What is the energy efficiency of a lamp that has 100J of electrical energy input and 42J of energy output wasted into the surroundings.

a)

0.58%

b)

58%

c)

0.55%

d)

55%

20.

The electrical energy used by a fan for 10s is 15J. Calculate the power of this fan in W.

a)

1.5W

b)

15W

c)

150W

d)

1500W