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Science (086) — AI-generated practice question

AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.

Q1. [1] medium exam-ready
A 100 W electric bulb and a 40 W electric bulb are both designed for 220 V. Which bulb has higher resistance? (A) The 100 W bulb (B) The 40 W bulb (C) Both have the same resistance (D) Cannot be determined from given data
  1. A The 100 W bulb
  2. B The 40 W bulb
  3. C Both have the same resistance
  4. D Cannot be determined from given data
Generated by claude-sonnet-4-6 · 2026-06-26 01:08 · grounding rag
Model Answer

(B) The 40 W bulb

Using $R = V^2/P$, the 40 W bulb has resistance $= 220^2/40 = 1210\ \Omega$, while the 100 W bulb has $220^2/100 = 484\ \Omega$. Lower power rating means higher resistance.

Source: Chapter 11 (Electricity), Section 11.8 Electric Power

Explanation

Key formula: $R = V^2/P$. Since both bulbs operate at the same voltage (220 V), resistance is inversely proportional to power. The lower the wattage, the higher the resistance. Examiners expect you to recall or derive $R = V^2/P$ from $P = V^2/R$.

Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.