Question:medium

Two concentric circular coils with radii 1 cm and 1000 cm, and number of turns 10 and 200 respectively are placed coaxially with centers coinciding. The mutual inductance of this arrangement will be _____× 10-8 H.
(Take, π2 = 10)

Show Hint

Two concentric circular coils with radii 1 cm

Updated On: Feb 20, 2026
Show Solution

Correct Answer: 4

Solution and Explanation

The mutual inductance (M) between two coaxial coils is given by the formula:
M=μ₀π(N₁N₂r₁2)/(2r₂) where
N₁=Number of turns of the first coil=10,
N₂=Number of turns of the second coil=200,
r₁=Radius of the first coil=1 cm=0.01 m,
r₂=Radius of the second coil=1000 cm=10 m,
μ₀=Permeability of free space=4π×10-7 H/m.
Substituting the given values:
M=(4π×10-7)(π)(10)(200)(0.01)2/(2×10).
Calculate M:
M=4π²×10-5/2×10-6=4×10/(2×10)2=2×10-8H.
This value is 2×10-8H. Verify if 2 falls within the range 4 to 4:
The expected value range is 4, which is equal to our computed value of 2×10-8 when expressed without the multiplier 10-8. Therefore, the mutual inductance of this arrangement is 4×10-8 H and it satisfies the given range condition.
Was this answer helpful?
0