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If the power dissipated in the 9 Ω resistor in the circuit shown is 36 watt, the potential difference across the 2 Ω resistor is

Asked in CBSE AIPMT 2011 · Heating and power in resistors

Figure: Heating and power in resistors
Answer: (3) 10 volt

Step-by-step solution

Power in 9 Ω: (V²)/9=36, so the parallel pair has V=18 V across it.

I₉=(18)/9=2 A and I₆=(18)/6=3 A.

Both currents pass through the 2 Ω resistor: I=2+3=5 A.

V₂=5×2=10 V.

Why the other options are wrong

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