Page 12 - English Class X_cbse new (FINAL).cdr

Q20 F igure shows three point charges, + 2q, –q, + 3q. Two charges + 2q and –q Q26 A sphere S1 othf erardaiudsiurs1er2n(rc2l>ors1e) sanadchthaerrgeeaQre, if there is another concentric
are enclosed within a surface ‘S’. What is the electric flux due to this config- sphere S2 of no additional charges between
uration through the surface ‘S’?
S1 and S2. Find the ratio of electric flux through S1 and S2.

[3] Delhi Set-1 [2009]

+2. q Q27 If the radius of the Gaussian surface enclosing a charge is halved, how
-q . S +3q does the electric flux through the Gaussian surface change?
[1] Delhi Set-3 [2010]
[3] OD Set-2 [2008]

Q21 Use Gauss's law to derive the expression for the electric field between two Q28 (a) Define electric flux. Write its SI units.
uniformly charged large parallel sheets with surface charge densities σ and
-σ respectively. (b) T he electric field components due to a charge inside the cube of side
0.1 m are as shown
[3] OD Set-2 [2009]
0.1m
Q22 Define electric flux. Write its S.I. unit. 0.1m
A charge q is enclosed by a spherical surface of radius R. If the radius is
Ex = αx, where α = 500 N/Cm
reduced to half, how would the electric flux through the surface change? Ey = 0, Ez = 0.
C alculate (i) the flux through the cube, and (ii) the charge inside the
[2] OD Set-1 [2009] cube.

Q23 ‘State Gauss's law in electrostatics. Using this law to derive an expression [5] OD Set-1 [2008]
for the electric field due to an infinitely long straight wire of linear charge
density 'σ' Cm-1. Q29 (a) U sing Gauss’s law, derive an expression for the electric field intensity
at any point outside a uniformly charged thin spherical shell of radius
[3] Delhi Set-3 [2009] R and charge density C/m2. Draw the field lines when the charge
density of the sphere is (i) positive, (ii) negative.
Q24 State Gauss’s law in electrostatics. Using this law derive an expression for
the electric field due to a uniformly charged infinite plane sheet. (b) A uniformly charged conducting sphere of 2.5 m in diameter has
a surface charge density of 100 μC/m2. Calculate the
[3] Delhi Set-2 [2009]
(i) charge on the sphere
Q25 A thin conducting spherical shell of radius R has charge Q spread uniformly
(ii) total electric flux passing through the sphere
over its surface. Using Gauss’s law, derive an expression for an electric field
[5] Delhi Set-1 [2008]
at a point outside the shell.

D raw a graph of electric field E(r) with distance r from the centre of the shell Q30 State Gauss’s theorem in electrostatics. Apply this theorem to derive an
expression for electric field intensity at a point outside a uniformly charged
for 0 ≤ r ≤ ∞ . thin spherical shell.

[3] Delhi Set-1 [2009] [3] Delhi Set-1 [2008, 2011]

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