Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE MainPhysicsMagnetic Effects of Current

A circular loop of radius R carries a steady current. The magnetic field at the centre of the loop is B₀ . At a distance x from the centre on the axis of the loop, the magnetic field is found to be B₀ 27 . The value of x is:

Options

  1. A2 2 R
  2. B3R
  3. C8R
  4. D26 R

Correct answer

A. 2 2 R

Step-by-step solution

The magnetic field at the centre of a circular loop of radius R is given by: B_ center = ₀ I 2R = B₀ The magnetic field at a distance x on the axis of the loop is: B_ axis = ₀ I R² 2(R² + x²)^ 3/2 Given that B_ axis = B₀ 27 , we can write the ratio as: B_ axis B_ center = R³ (R² + x²)^ 3/2 = 1 27 Taking the cube root of both sides: R R² + x² = 1 3 Squaring both sides: R² R² + x² = 1 9 R² + x² = 9R² x² = 8R² x = 2 2 R Answer: 2 2 R

Practice Magnetic Effects of Current on Quantrex Academy →

More from Magnetic Effects of Current

A hollow, right circular cone of base radius R and height h , with its tip at the origin is rotating about the Z -axis with an angular velocity , as shown in the figure. The cone c 2026In a vacuum chamber, a particle of charge 1 C and mass 1 mg is projected with a velocity ( i + 2 j ) ms ⁻¹ from the XZ plane at time t = 0 in an electric field of 1 i Vm ⁻¹ . At t 2026A current carrying circular loop of radius 2 cm with unit normal n = k + i 2 is placed in a magnetic field, B = B₀(3 i +2 k ) . If B₀ = 4 10⁻³ T and current I=100 2 A, the torque e 2026A 5 mg particle carrying a charge of 5 10⁻⁶ C is moving with velocity of (3 i +2 k ) 10⁻² m/s in a region having magnetic field B = 0.1 k Wb/m ^2 . It moves a distance of meter alo 2026A current of 30 A each flows in opposite directions in two conducting wires, placed parallel to each other at a distance of 8 cm. The magnetic field at the mid point between the tw 2026A small cube of side 1 mm is placed at the centre of a circular loop of radius 10 cm carrying a current of 2 A. The magnetic energy stored inside the cube is 10⁻¹⁴ J. The value of 2026The charged particle moving in a uniform magnetic field of (3 i + 2 j ) T has an acceleration (4 i - x 2 j ) m/s ^2 . The value of x is __________. 2026A circular coil of radius 2 cm and 125 turns carries a current of 1 A. The coil is placed in a uniform magnetic field of magnitude 0.4 T. The axis of the coil makes an angle of 30° 2026 Full Magnetic Effects of Current list All JEE Main PYQs