F5 Chapter 3.4 Electrical energy and power

50W is equivalent to which of the following?

• C. 50Vs-1

How many joules of electrical energy are use in a 6V,0.5A bulb in 2 minutes?

• A. 3J

• B. 6J

• C. 180J

• D. 360J

Killowatt-hour (kWh) is a unit of

• time

• energy

• speed

• Power

An electrical lamp is rated 250V,100W. When it is used, what is the current flowing through its filament?

• 0.2A

• 0.4A

• 0.6A

• 0.8A

An electrical appliance which is rated 240V, 5000W is switch on for 10 hours each day. What is the cost of operating the appliance for a week? The electricity tariff is show in the table below.

• RM75.50

• RM88.00

• RM104..20

• RM98.50

• 250W

• 760W

• 840W

• 930W

• 
• 
• 
• 

Why rice in pot B cook faster?

• Energy release is lower.

• Energy release is higher

• The rate of energy release is lower

• The rate of energy release is higher

9

• 3.45A

• 5.67A

• 7.90A

• 9.17A

10. Which of the following step is the correct way to reduce the energy consumption in daily life?

• A. Do not turn on the refrigerator.
• B. Do not wash the cloth when the cloth is not dirty.
• C. Charge the phone only when you need to use it
• D. Turn off the air-conditioner when it is not in used