Question:
10 W is to be delivered to a device via a wire having resistance \(2\,\Omega\). If 20 V is the voltage across the device, the power wasted in the process is:
10 W is to be delivered to a device via a wire having resistance \(2\,\Omega\). If 20 V is the voltage across the device, the power wasted in the process is:
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Use \(P_{loss} = I^2R\) when current is known; use \(VI\) only when voltage drop is required.
Updated On: Jun 19, 2026
- 3 W
- 2 W
- 0.5 W
- 1.5 W
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The Correct Option is C
Solution and Explanation
Step 1: Find current required by device.
Power delivered: \[ P = VI \] \[ 10 = 20 \times I \Rightarrow I = 0.5\,A \]
Step 2: Voltage drop in wire.
\[ V_{loss} = IR = 0.5 \times 2 = 1\,V \]
Step 3: Power loss in wire.
\[ P_{loss} = I^2R = (0.5)^2 \times 2 \]
Step 4: Simplify.
\[ P_{loss} = 0.25 \times 2 = 0.5\,W \]
Step 5: Physical interpretation.
Power loss occurs due to Joule heating in transmission wire.
Step 6: Final conclusion.
Thus, wasted power is: \[ \boxed{0.5\,W} \]
Power delivered: \[ P = VI \] \[ 10 = 20 \times I \Rightarrow I = 0.5\,A \]
Step 2: Voltage drop in wire.
\[ V_{loss} = IR = 0.5 \times 2 = 1\,V \]
Step 3: Power loss in wire.
\[ P_{loss} = I^2R = (0.5)^2 \times 2 \]
Step 4: Simplify.
\[ P_{loss} = 0.25 \times 2 = 0.5\,W \]
Step 5: Physical interpretation.
Power loss occurs due to Joule heating in transmission wire.
Step 6: Final conclusion.
Thus, wasted power is: \[ \boxed{0.5\,W} \]
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