Electricity (HAVO)

Which unit is commonly used to indicate the power of an electrical device?

• Watt (W)

• Volt (V)

• Ampere (A)

• Joule (J)

What is 1 kW in watts (W)?

• 10 W

• 100 W

• 1000 W

• 10,000 W

Answer explanation

1 kW (kilowatt) is equal to 1000 watts (W). Therefore, the correct answer is 1000 W.

What unit is used to indicate the current of an electrical device?

• Watt (W)

• Volt (V)

• Ampere (A)

• Joule (J)

Answer explanation

The current of an electrical device is measured in Amperes (A). Watts (W) measure power, Volts (V) measure voltage, and Joules (J) measure energy. Therefore, the correct unit for current is Ampere (A).

If a lamp operates at a voltage of 12 V and a current of 220 A, what is the power?

• 2200 W

• 1200 W

• 264 W

• 2640 W

Answer explanation

Power is calculated using the formula P = V × I. Here, P = 12 V × 220 A = 2640 W. Therefore, the correct answer is 2640 W.

What is the formula to calculate the energy consumption of an electrical device?

• Power = Voltage / Current

• Power = Watts / Current

• Power = Watts * Current

• Power = Voltage * Current

If a Tesla Model Y has a power of 220,000 Watts, that is the same as ........ kW

In a device, all the different components have a certain power, the total power of the device is the sum of the powers of the components.

• True

• False

Answer explanation

The statement is true because the total power of a device is indeed calculated by summing the power of all its individual components.

The energy in natural gas is converted into heat in the ___________ .
This heat is used to turn water into steam that then drives a ________________ .
This makes a  ____________ rotate, generating electrical energy.

A LED light with a rating of 4.20 W is lit for 180 s.

What is the energy consumed by the LED light?

• The energy consumed by the LED light is 756J.

• The energy consumed by the LED light is 780J.

• The energy consumed by the LED light is 756W.

• The energy consumed by the LED light is 780W.

Answer explanation

To find the energy consumed, use the formula: Energy (J) = Power (W) × Time (s). Here, Energy = 4.20 W × 180 s = 756 J. Thus, the correct answer is that the energy consumed by the LED light is 756J.

Transformers only work on alternating voltages.
There is a magnetic field in the iron core of a transformer that is constantly changing its direction and size.

• True

• False

Answer explanation

True. Transformers operate on alternating current (AC), which creates a changing magnetic field in the iron core. This changing field is essential for inducing voltage in the secondary coil.