Young Scientists_1

To measure the voltage between 2 points of an electric circuit, we can use ___________

• a circuit breaker

• a multimeter set as an ohmmeter

• a multimeter set as ammeter

• a multimeter set as a voltmeter

Which of the following is not a safety device?

• circuit breaker

• fuse

• earth wire

• damaged insulation

An electric iron with a power of 1500W was used for 2 hours.

(a) Calculate the energy used in KWh

(b) If 1KWh of electricity is sold for 20 cents, calculate the cost.

Answer explanation

(a) 3KWh

(b) $0.60

What is the power of a 20V bulb with 5A through it?

• 100W
• 100V
• 6.3W
• 6.3A

What is the current through a 11V bulb with a power of 99W?

• 9W
• 9A
• 60V
• 60A

If the battery produced 12.6 Volts and what would be the current flow be for a 6 Ohm resistor

• 2.1 Amps
• 2.4 Amps
• 1.71 Amps
• 15 Amps

An electric kettle is found to use 36 000 J of electrical energy in 30 seconds. What is the power of the kettle?

• 1200 W

• 18 000 W

• 72 000W

• 1080 000 W

Which part of an electric iron is the earth wire attached to?

• the heating element

• the live wire

• the metal case

• the plastic handle

An electric heater uses a current of 8 A when connected to a 250 V supply.

How much energy is converted by the heater in 1 minute?

• 2000 J

• 16 000 J

• 120 000 J

• 960 000 J