ExamBro
ExamBro
CUET · PHYSICS · PYQ PAPER 2025

The ratio of magnetic fields at the centre of a current carrying a circular loop of radius 16 cm and at a point on its axis at a distance r from its centre is 125 : 64. The value of r is

  1. A 6 cm
  2. B 9 cm
  3. C 12 cm
  4. D 15 cm
Verified Solution

Answer & Solution

Correct Answer

(C) 12 cm

Step-by-step Solution

Detailed explanation

\( \frac{B_{centre}}{B_{axis}} = \frac{(R^2 + r^2)^{3/2}}{R^3} \) \( \frac{125}{64} = \frac{(R^2 + r^2)^{3/2}}{R^3} \) \( \left(\frac{125}{64}\right)^{1/3} = \frac{(R^2 + r^2)^{1/2}}{R} \) \( \frac{5}{4} = \frac{\sqrt{R^2 + r^2}}{R} \) \( \frac{5R}{4} = \sqrt{R^2 + r^2} \)…
Same subject
Explore more questions on app