The source of time varying magnetic field may be
(A) a permanent magnet
(B) an electric field changing linearly with time
(C) direct current
(D) a decelerating charge particle
(E) an antenna fed with a digital signal
Choose the correct answer from the options given below:
(A) a permanent magnet
(B) an electric field changing linearly with time
(C) direct current
(D) a decelerating charge particle
(E) an antenna fed with a digital signal
Choose the correct answer from the options given below:
- (A)(D) only✓ Correct
- (B)(C) and (E) only
- (C)(A) only
- (D)(B) and (D) only
Answer: (A)
Solution
A time-varying magnetic field requires an accelerating or decelerating charge.
(A) A permanent magnet produces a static magnetic field.
(B) An electric field changing linearly with time produces a constant current (by Maxwell's displacement current), which generates a constant (not time-varying) magnetic field.
(C) Direct current produces a static magnetic field.
(D) A decelerating charge particle is an accelerated charge (negative acceleration), which produces time-varying electric and magnetic fields.
(E) A digital signal in an antenna involves constant voltage levels (not continuously varying), producing static fields during each level.
Only (D) produces a time-varying magnetic field.
(A) A permanent magnet produces a static magnetic field.
(B) An electric field changing linearly with time produces a constant current (by Maxwell's displacement current), which generates a constant (not time-varying) magnetic field.
(C) Direct current produces a static magnetic field.
(D) A decelerating charge particle is an accelerated charge (negative acceleration), which produces time-varying electric and magnetic fields.
(E) A digital signal in an antenna involves constant voltage levels (not continuously varying), producing static fields during each level.
Only (D) produces a time-varying magnetic field.
JEE Main · 2023 · 13 Apr 2023 · Shift 1 · Single correct option