A point charge causes an electric flux of −1.0 × 103 Nm2/C to pass through a spherical Gaussian surface of 10.0 cm radius centred on the charge. - Physics

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Numerical

A point charge causes an electric flux of −1.0 × 103 Nm2/C to pass through a spherical Gaussian surface of 10.0 cm radius centred on the charge.

(a) If the radius of the Gaussian surface were doubled, how much flux would pass through the surface?

(b) What is the value of the point charge?

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Solution

(a) Electric flux, Φ = −1.0 × 103 N m2/C

Radius of the Gaussian surface,

r = 10.0 cm

Electric flux piercing out through a surface depends on the net charge enclosed inside a body. It does not depend on the size of the body. If the radius of the Gaussian surface is doubled, then the flux passing through the surface remains the same i.e., −103 N m2/C.

(b) Electric flux is given by the relation,

`phi = "q"/in_0`

Where,

q = Net charge enclosed by the spherical surface

0 = Permittivity of free space = 8.854 × 10−12 N−1 Cm−2

∴ `"q" = phiin_0`

= −1.0 × 103 × 8.854 × 10−12

= −8.854 × 10−9 C

= −8.854 nC

Therefore, the value of the point charge is −8.854 nC.

Concept: Electric Flux
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Chapter 1: Electric Charges and Fields - Exercise [Page 48]

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NCERT Physics Class 12
Chapter 1 Electric Charges and Fields
Exercise | Q 1.20 | Page 48
NCERT Physics Class 12
Chapter 1 Electric Charge and Fields
Exercise | Q 20 | Page 48

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