learnohub
Question:
a conducting loop of radius r is placed concenteric with another loop of a much larger radius R so that both loop are coplanar find the mutual inductance of the system of the two loop take R>>r
Answer:

Coaxial coils mutual inductance

Let the current I pass through the outer coil of radius R. Due to this the magnetic field at the centre of the coil will be B = µ0 I / 2R

As it is given that R >> r, we can consider the magnetic field B to be constant over the entire cross-sectional area of the inner coil of radius r. Hence, flux associated with the small coil will be Ф1 = BA1 = B ∏ r2

Ф1 = (µ0 I / 2R) * ∏ r2

By the definition of mutual inductance Ф1 = M12 I2 = M12 I

Hence, M21 = M = M12 = Ф1 / I

        = (µ0 I / 2R) * ∏ r2 * (1/I)

        = µ0 ∏ r2 / 2R

The value of M shows that it is independent of the value of current and depends on radius of the two coils only.

Not what you are looking for? Go ahead and submit the question, we will get back to you.

learnohub

Classes

  • Class 6
  • Class 7
  • Class 8
  • Class 9
  • Class 10
  • Class 11
  • Class 12
  • ICSE 6
  • ICSE 7
  • ICSE 8
  • ICSE 9
  • ICSE 10
  • NEET
  • JEE

YouTube Channels

  • LearnoHub Class 11,12
  • LearnoHub Class 9,10
  • LearnoHub Class 6,7,8
  • LearnoHub Kids

Overview

  • FAQs
  • Privacy Policy
  • Terms & Conditions
  • About Us
  • NGO School
  • Contribute
  • Jobs @ LearnoHub
  • Success Stories
© Learnohub 2026.