KVPY SX SB Exam 2015 Question Paper

Question : 29 of 120

Marks: +1, -0

A point charge Q(= 3 × 10

^{-12}

C) rotates uniformly in a vertical circle of radius R =1 mm. The axis of the circle is aligned along the magnetic axis of the earth. At what value of the angular speed ω, the effective magnetic field at the center of the circle will be reduced to zero ? (Horizontal component of Earth's magnetic field is 30 micro Tesla)

10 $^{11}$ rad/s
10 $^{9}$ rad/s
10 $^{13}$ rad/s
10 $^{7}$ rad/s

Validate

Solution:

B =(µ_0/{4π})({Qω}/R)

B = B_H

(at centre effective magnetic field become zero)

{µ_0Qω}/{4πR}=B_H

ω={B_H(4πR)/{µ_0Q}

(BH = 30 × 10^{–6} T; R = 1 mm; Q = 3 × 10^{–12}C)

ω = 10^11

rad/s

Go to Question:

Prev Question

Next Question