CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

A point charge Q is located on the axis of a disc of radius R at a distance b from the plane of the disc. If one-fourth of the total electric flux from the charge passes through the disc, then choose the correct option.

A
R=3b
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
3R=b
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
2R=3b
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
R=2b3
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is A R=3b
From the concept of solid angle we know that, solid angle subtended by disc is 2π(1cosθ)

Since the flux through the solid angle 4π is
ϕtotal=Qε0...(1)
So, the flux through disc with solid angle 2π(1cosθ) will be

ϕdisc=2π(1cosθ)Qε0(4π)

ϕdisc=(1cosθ)Q2ε0...(2)

From (1) and (2) we have,
ϕdisc=(ϕtotal)(1cos θ2) (3)

According to question, ϕdisc=14(ϕtotal) (4)

From equation (3) and (4) we get,
14=(1cos θ2)
cosθ=12
θ=60

From above figure,
Rb=tan 60=3
R=3b

Hence option (a) is correct answer.

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Visualising Electric Fields - Electric Field Lines
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon