Question

An a particle is moving along a circle of radius R with a constant angular velocity w. Point A lies in the same plane at a distance 2R from the centre. Point A records magnetic field produced by a particle, if the minimum time interval between two successive times at which A records zero magnetic field is 't' the angular speed w, in terms of t is :

• A. $\frac { 2 \pi } { \mathrm { t } }$
• B.
• C. $\frac { \pi } { 3 \mathrm { t } }$
• D.

Answer 1

Answer: (B)

Answer 2

Point A shall record zero magnetic field (due to a-particle) is at position P and Q as shown in figure. The time taken by a-particle to go from P to Q is–

t = $\frac { 1 } { 3 }$ $\frac { 2 \pi } { \omega }$ or w = $\frac { 2 \pi } { 3 t }$