Physics Circle home Student Login

Home›Chapters›Moving Charges and Magnetism PYQs›Magnetic Field of Straight Wires›Question 54

MHT CET 2020 (16 Oct, Shift 2) · Magnetic Field of Straight Wires

Magnetic Field of Straight Wires question from MHT CET 2020 (16 Oct, Shift 2)

Q54MHT CET 2020 · 16 OCT · SHIFT 2Medium

Magnetic Field of Straight Wires

A circular coil of radius RR is carrying a current I1I_1 in anti-clockwise sense. A long straight wire is carrying current I2I_2 in the negative direction of XX-axis. Both are placed in the same plane and the distance between centre of coil and straight wire is dd. The magnetic field at the centre of coil will be zero for the value of dd equal to

Show answer and solution

Answer: (a)

  1. Coil at centre: B1=μ0I12RB_1 = \frac{\mu_0 I_1}{2R}; wire at distance dd: B2=μ0I22πdB_2 = \frac{\mu_0 I_2}{2\pi d}.
  2. The directions are opposite, so B=0B = 0 when μ0I12R=μ0I22πd\frac{\mu_0 I_1}{2R} = \frac{\mu_0 I_2}{2\pi d}.
  3. d=Rπ(I2I1)d = \frac{R}{\pi}\left(\frac{I_2}{I_1}\right)
  4. So the answer is (a).
Report a mistake

More questions on Magnetic Field of Straight Wires