Verified Solution • 2025–26 Session moderate

QPages 277-278: Q19: HC Verma: Concepts of Physics - Volume 2 Permanent Magnets Pages 277-278: Q19 Solution: The magnetometer of the previous problem is used with the same…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students frequently confuse the Tan-B position formula with the Tan-A position, incorrectly using $d^2$ in the denominator instead of the correct $(d^2 + l^2)^{3/2}$ (which simplifies to $d^3$ for a short magnet). Always verify the geometric orientation: Tan-B requires the cube of the distance, not the square.

The magnetometer of the previous problem is used with the same magnet in Tan-B position. Where should the magnet be placed to produce a 37� deflection of the needle?

Step-by-Step Verified Solution

**Answer:**

d = 7.9 \text{ cm}

. **Step-by-Step Explanation:** Using

M/B_H = 3.75 \times 10^3

and Tan-B position formula with

\theta = 37�

:

\tan 37� = \frac{\mu_0}{4\pi} \frac{M}{(d^2 + l^2)^{3/2} B_H}

. For short magnet:

0.75 = 10^{-7} \times \frac{3.75 \times 10^3}{d^3}

.

d^3 = \frac{3.75 \times 10^{-4}}{0.75} = 5 \times 10^{-4} \Rightarrow d = 0.079 \text{ m} = 7.9 \text{ cm}

[citation:4].

All Questions in this Chapter

QPage 276: Q1 QPage 276: Q2 QPage 276: Q3 QPage 276: Q4 QPage 276: Q5 QPage 276: Q6 QPage 276: Q7 QPage 276: Q8 QPage 276: Q9 QPage 276: Q10 QPage 276: Q11 QPage 276: Q12 QPage 276: Q13 QPage 277: Q1 QPage 277: Q2 QPage 277: Q3 QPage 277: Q4 QPage 277: Q5 QPages 275-276: Q1 QPages 275-276: Q2 QPages 275-276: Q3 QPages 275-276: Q4 QPages 275-276: Q5 QPages 275-276: Q6 QPages 275-276: Q7 QPages 275-276: Q8 QPages 275-276: Q9 QPages 275-276: Q10 QPages 275-276: Q11 QPages 277-278: Q1 QPages 277-278: Q2 QPages 277-278: Q3 QPages 277-278: Q4 QPages 277-278: Q5 QPages 277-278: Q6 QPages 277-278: Q7 QPages 277-278: Q8 QPages 277-278: Q9 QPages 277-278: Q10 QPages 277-278: Q11 QPages 277-278: Q12 QPages 277-278: Q13 QPages 277-278: Q14 QPages 277-278: Q15 QPages 277-278: Q16 QPages 277-278: Q17 QPages 277-278: Q18 QPages 277-278: Q19 QPages 277-278: Q20 QPages 277-278: Q21 QPages 277-278: Q22 QPages 277-278: Q23 QPages 277-278: Q24 QPages 277-278: Q25

Related Learning Resources & Exam Preparation

Chapter Practice Bank

Practice all topic-wise questions from Permanent Magnets

Reference Textbook Solutions

Explore complete chapter exercises for HC Verma: Concepts of Physics - Volume 2

Competitive PYQ Question Bank

Browse year-wise authentic previous years' questions with solutions

Authentic CBT Mock Tests

Simulate official exam environment with live timer and percentile scoring