An electric heater is rated 1500W. How much energy does it use in 10 hours ?

Explanation

To solve the problem of how much energy an electric heater rated at 1500W uses in 10 hours, we can follow these steps:

### Step 1: Understand the relationship between power, energy, and time.
Power (in watts) is defined as the rate at which energy is consumed or produced. The formula relating power (P), energy (E), and time (t) is:
\[ P = \frac{E}{t} \]
From this, we can rearrange the formula to find energy:
\[ E = P \times t \]

### Step 2: Identify the values given in the problem.
- Power (P) = 1500 watts
- Time (t) = 10 hours

### Step 3: Convert time into a consistent unit if necessary.
Since the power is given in watts (which is equivalent to joules per second), we can convert hours into seconds if we want to express energy in joules. However, since we are calculating energy in watt-hours, we can keep the time in hours.

### Step 4: Calculate the energy consumed.
Using the formula from Step 1:
\[ E = P \times t \]
Substituting the known values:
\[ E = 1500 \, \text{W} \times 10 \, \text{h} \]
\[ E = 15000 \, \text{Watt-hours} \]

### Step 5: Convert watt-hours to kilowatt-hours.
Since 1 kilowatt (kW) = 1000 watts (W), we can convert watt-hours to kilowatt-hours:
\[ E = \frac{15000 \, \text{Watt-hours}}{1000} \]
\[ E = 15 \, \text{kWh} \]

### Final Answer:
The electric heater uses **15 kilowatt-hours (kWh)** of energy in 10 hours.

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