Physics Circle home Student Login

Home›Chapters›Electromagnetic Waves PYQs›Displacement Current, Maxwell's Equations & Production›Question 14

JEE Main 2013 (23 Apr, Shift 1) · Displacement Current, Maxwell's Equations & Production

Displacement Current, Maxwell's Equations & Production question from JEE Main 2013 (23 Apr, Shift 1)

Q14JEE Main 2013 · 23 APR · SHIFT 1Difficult

Displacement Current, Maxwell's Equations & Production

A parallel plate capacitor of area 60 cm2^{2} and separation 3 mm is charged initially to 90μ\muC. If the medium between the plate gets slightly conducting and the plate loses the charge initially at the rate of 2.5×10−82.5 \times 10^{-8} C/s, then what is the magnetic field between the plates?

Show answer and solution

Answer: (d)

  1. Charge leaks through the medium, so a conduction current Ic=−dqdtI_c = -\dfrac{dq}{dt} flows from the positive to the negative plate.
  2. The field falls, giving displacement current Id=ε0dϕEdt=dqdtI_d = \varepsilon_0 \dfrac{d\phi_E}{dt} = \dfrac{dq}{dt}, equal in size and opposite in direction.
  3. Total current between the plates Ic+Id=0I_c + I_d = 0, so by Ampere-Maxwell law B=0B = 0.
  4. So the answer is (d) zero.
Report a mistake

More questions on Displacement Current, Maxwell's Equations & Production