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NDA 2021 GAT · General Knowledge · Current Electricity · hard

An electric heater is rated 1000 W at 220 V. Its resistance when working normally is nearly

Single correct option

An electric heater is rated 1000 W at 220 V. Its resistance when working normally is nearly
  1. A. 4.5 ohm
  2. B. 22 ohm
  3. C. 48.4 ohm
  4. D. 220 ohm
Show answer and solution

Answer: (C) 48.4 ohm

From P = V^2/R, R = 220 x 220 / 1000 = 48.4 ohm. The current is about 4.5 A, which is a common wrong choice if the current is mistaken for resistance. Using R = V/P or R = V gives meaningless values such as 0.22 or 220.
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Original question written in the NDA 2021 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake