Science — CBSE Class 10 board question

Given: V = 230 V, P = 1000 W

Using the formula $P = \dfrac{V^2}{R}$, we get:

$$R = \frac{V^2}{P} = \frac{(230)^2}{1000} = \frac{52900}{1000} = 52.9 \ \Omega$$

The resistance of the heating element is 52.9 Ω.

Source: Electric Power, Section 11.8, Chapter 11 – Electricity

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• Examiners expect you to state the formula used, substitute values, and arrive at the answer with units.
• The key formula here is $P = V^2/R$, rearranged to $R = V^2/P$. This comes directly from Section 11.8.
• Do not use $P = VI$ first to find current — it is an extra step and wastes time; the direct formula is cleaner and preferred.
• Always include the unit Ω in your final answer for full marks.