Page 10 - English Class X_cbse new (FINAL).cdr

Q1 (a) Define electric flux. Is it a scalar or a vector quantity ? Q5 (a) "Gauss's law in electrostatics is true for any closed surface, no matter
what its shape or size is." Justify this statement with the help of a suit-
A point charge q is at a distance of d/2 directly above the centre of a
square of sided, as shown in the figure. Use Gauss' law to obtain the able example.
expression for the electric flux through the square.
(b) U se Gauss's law to prove that the electric field inside a uniformly
charged spherical shell is zero.

[5] OD Set-1 [2015]

Q6 A thin metallic spherical shell of radius R carries a charge Q on its surface.

A point charge Q is placed at its centre C and an other charge +2Q is
2
placed outside the shell at a distance x from the centre as shown in the

(b) If the point charge is now moved to a distance 'd' from the centre of figure. Find (i) the force on the charge at the centre of shell and at the point
the square and the side of the square is doubled, explain how the A, (ii) the electric flux through the shell.
electric flux will be affected .

OR

( ) (a) Use Gauss' law to derive the expression for the electric field E due

to a straight uniformly charged infinite line of charge density l C/m.

(b) Draw a graph to show the variation of E with perpendicular distance r [5] OD Set-3 [2015]
from the line of charge.

(c) Find the work done in bringing a charge q from perpendicular distance

r1 to r2 (r2 > rl). Q7 W hat is the electric flux through a cube of side 1 cm which encloses an
electric dipole?
[5] OD [2018]

[1] Delhi Set-1 [2015]

Q2 (a) U se Gauss’s theorem to find the electric field due to a uniformly Q8 Consider two hollow concentric spheres, S1 and S2, enclosing charges 2Q
charged infinitely large plane thin sheet with surface charge density σ. and 4Q respectively as shown in the figure.

(b) A n infinitely large thin plane sheet has a uniform surface charge densi- 4Q
ty + σ. Obtain the expression for the amount of work done in bring-
ing a point charge q from infinity to a point, distant r, in front of the 2Q S2
charged plane sheet.

[5] OD Set-1 [2017]

Q3 How does the electric flux due to a point charge enclosed by a spherical S1
Gaussian surface get affected when its radius is increased?

[1] Delhi Set-1 [2016] (i) Find out the ratio of the electric flux through them. (ii) How will the
electric flux through the sphere S1 change if a medium of dielectric
Q4 Use Gauss's law to find the electric field due to a uniformly charged infinite constant 'εr' is introduced in the space inside S1 in place of air? Deduce
the necessary expression.
plane sheet. What is the direction of field for positive and negative charge

densities? [5] OD Set-1 [2014]

[3] OD Set-1 [2016]

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