Verified Solution • 2025–26 Session moderate

QPages 218-219: Q8: HC Verma: Concepts of Physics - Volume 2 Thermal and Chemical Effects of Electric Current Pages 218-219: Q8 Solution: An electric bulb marked 220 V, 100 W will get fused if it is…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often think the question asks for the change in voltage (270 V − 220 V = 50 V). In fact, the problem asks for the absolute voltage that will produce 150 W, so you must compute $V_{max}=sqrt{P_{max}R}$ using the rated resistance. Do not subtract from the nominal voltage.

An electric bulb marked 220 V, 100 W will get fused if it is made to consume 150 W or more. What voltage fluctuation will the bulb withstand?

Step-by-Step Verified Solution

**Answer:**

V = 270

V. **Step-by-Step Explanation:**

R = 220^2/100 = 484\ \Omega

. For

P = 150

W:

V = \sqrt{PR} = \sqrt{150 \times 484} = 269.4 \approx 270

V .

All Questions in this Chapter

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