NCERT Class XII Chapter
Electric Charges and Fields
Questions With Solutions
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Question : 18
Total: 34
A point charge +10 μC is at a distance of 5 cm directly above the centre of a square of side 10 cm, as shown in figure. What is the magnitude of the electric flux though the square?
Solution:
Let us assume that the given square be one face of the cube of edge 10 cm.
As charge of +10 μC is at a distance of 5 cm above the centre of a square, so it is enclosed by the cube.
Hence by Gauss’s theorem, electric flux linked with the cube is
ϕ =
=
= 1.13 × 10 6 N m 2 C − 1
So, the magnitude of the electric flux through the square is
ϕ s q =
=
× 10 6 or ϕ s p = 1.9 × 10 5 N m 2 C − 1
As charge of +10 μC is at a distance of 5 cm above the centre of a square, so it is enclosed by the cube.
Hence by Gauss’s theorem, electric flux linked with the cube is
ϕ =
So, the magnitude of the electric flux through the square is
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