Question

An electrical appliance is rated 1500 W, 250 V. This appliance is connected to a 250 V supply mains. The current drawn by the appliance (assuming unity power factor) is:

• A. 16 A
• B. 6 A
• C. 15 A
• D. 12 A

Hint:

Power is the product of voltage and current for resistive loads. For a rated appliance, simply divide the power by the voltage to find the current.

Answer 1

The Correct Option is B

Step 1: Find the appliance's resistance from its rating: \(R=\dfrac{V^2}{P}=\dfrac{250^2}{1500}=\dfrac{62500}{1500}\approx41.67\,\Omega\).

Step 2: Since the supply voltage matches the rated voltage exactly, apply Ohm's law: \(I=\dfrac{V}{R}\).

Step 3: Substitute: \(I=\dfrac{250}{41.67}\approx6\,\text{A}\).
\[ \boxed{I = 6\,\text{A}} \]

Answer 2

Since the appliance is plugged into precisely the voltage it was rated for, it draws exactly its rated current, with no adjustment needed for over- or under-voltage. At 250 V, every 1 A drawn corresponds to 250 W of power, because \(1\,\text{A}\times250\,\text{V}=250\,\text{W}\).

The appliance is rated for 1500 W, and dividing this by 250 W per amp shows it must draw \(1500\div250=6\) amps. \[I = 6\,\text{A}\]