A 2 kW electric heater operates for 45 minutes on its rated supply. How much electrical energy does it consume?
1.5 kWh
To determine the electrical energy consumed by a 2 kW electric heater operating for 45 minutes, we need to use the formula for electrical energy consumption:
\(E = P \times t\)
Where:
- \(E\) is the energy consumed in kilowatt-hours (kWh),
- \(P\) is the power in kilowatts (kW), and
- \(t\) is the time in hours (h).
Given:
- Power, \(P = 2\) kW
- Time, \(t = 45\) minutes
First, we convert the time from minutes to hours since power is given in kilowatts:
\(t = \frac{45}{60} = 0.75\) hours
Substituting the known values in the formula:
\(E = 2 \, \text{kW} \times 0.75 \, \text{hours} = 1.5 \, \text{kWh}\)
Therefore, the electrical energy consumed by the heater is 1.5 kWh.
This means the correct option is: 1.5 kWh
Let's evaluate other options:
- \(5.4 \, \text{kWh}\): This is too high for the given power and time.
- \(0.75 \, \text{kWh}\): This would result if the power were only 1 kW.
- \(90 \, \text{kWh}\): This is too high and unrealistic for 45 minutes.
Hence, 1.5 kWh is the correct answer as verified by calculation.
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