A 100-turn closely wound circular coil of radius 5cm has a magnetic field 3.14× 10⁻³T at its centre. The current flowing through the coil, and the magnitude of the magnetic moment of the coil are, respectively - (Take μ₀ = 4π × 10⁻⁷Tm / A)

Solution & Explanation

Related Formula
B₀ = μ₀Ni2R M = NiA = Ni(π R²)
Core Logic

Step 1: Calculate current i:

i = 2RB₀μ₀N = 2× 5× 10⁻²× 3.14× 10⁻³4π× 10⁻⁷× 100 = 2.5A

Step 2: Calculate magnetic moment M:

M = NiA = 100× 2.5× 3.14× (5× 10⁻²)² = 2Am²
Pattern Recognition

Standard formula application for circular coil central magnetic field and magnetic dipole moment.

Chapter Mix

Class 12 Physics: Magnetic Effects of Current and Magnetism

Reference Study Guides

Magnetic Effects Of Current And Magnetism

More Magnetic Effects of Current and Magnetism Previous-Year Questions

Q8 neet_2024_05_may_morning Ampere's Circuital Law Application
The figure given below shows a long straight solid wire of circular cross-section of radius 'a' carrying steady current I. The current I is uniformly distributed across its cross-section. The plot which correctly represents the variation of magnetic field (B) with distance (r) from the axis of the conductor in the region is
Ampere's Circuital Law Application diagram for Q8 - NEET 2026 Code 12
Cross section of solid current-carrying conductor of radius a.
  • A. Option (1)
  • B. Option (2)
  • C. Option (3)
  • D. Option (4)

Solution

Related Formula
B = μ₀Ir2π a² (r < a) B = μ₀I2π r (r > a)
Core Logic

Inside the conductor (r < a), B ∝ r (linear increase). Outside the conductor (r > a), B ∝ (1)/(r) (hyperbolic decrease).

B vs r plot solution for Q8
Cross section of solid current-carrying conductor of radius a.

This behavior is correctly depicted in option (1).

Pattern Recognition

Solid cylinder magnetic field graph increases linearly inside and decreases hyperbolically outside.

Chapter Mix

Class 12 Physics: Magnetic Effects of Current and Magnetism

More Magnetic Effects of Current and Magnetism Questions — neet_2024_05_may_morning

Practice all Magnetic Effects of Current and Magnetism previous-year questions →

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