MCQs of Electric Charges and Electric Fields

Electric Charges and Electric Fields MCQs

MCQs of Electric Charges and Electric Fields

Showing 131 to 140 out of 141 Questions

131.

The charge density in a cubic box is given by βxyz. If length of the box is L, then the total charge on it is _____.

(a)	3βL³
(b)	$β \frac{L^{6}}{6}$
(c)	βL³
(d)	$β \frac{L^{6}}{8}$

132.

The distance between charges q and 9q is 60 cm. At what distance, the electric field intensity will be zero on the line joining these charges?

(a)	At 30 cm from q
(b)	At 45 cm from 9q
(c)	At 20 cm from q
(d)	At 15 cm from 9q

133.

An electric dipole moment

\vec{p}

is placed in an uniform electric field of intensity

\vec{E}

parallel to the field. The work required to rotate it through an angle θ is _____.

(a)	$\vec{p} \times \vec{E}$
(b)	$p E (1 - \sin θ)$
(c)	$\vec{p} . \vec{E}$
(d)	$p E (1 - \cos θ)$

134.

Radius of a spherical shell is 1 m and uniform surface charge density of charge distributed is

\frac{1}{π} \frac{C}{m^{2}}

. If a spherical shell of radius 2 m is imagine concentric, then what is the electric field intensity at each point on the surface of this shell?

(a)	9 × 10⁹ N/C
(b)	10¹⁰ N/C
(c)	π N/C
(d)	4π N/C

135.

If the electric flux entering and leaving an enclosed surface is

ϕ_{1} and ϕ_{2}

respectively, then the electric charge inside the surface will be _____.

(a)	$(ϕ_{1} + ϕ_{2}) ε_{0}$
(b)	$\frac{ϕ_{1} + ϕ_{2}}{ε_{0}}$
(c)	$(ϕ_{2} - ϕ_{1}) ε_{0}$
(d)	$\frac{ϕ_{2} - ϕ_{1}}{ε_{0}}$

136.

A hollow cylinder has a charge q coulomb within it. If Φ is the electric flux in units of volt-meter associated with the curved surface B, then the flux linked with the plane surface A in units of volt-meter will be _____.

(a)	$\frac{1}{2} \frac{q}{ε_{0}}$
(b)	$\frac{q}{ε_{0}} - ϕ$
(c)	$\frac{1}{2} (\frac{q}{ε_{0}} - ϕ)$
(d)	$\frac{ϕ}{3}$

137.

A pendulum bob of mass 80 mg carrying a charge of 2 × 10^-8 C is at rest in an uniform horizontal electric field E = 20000 V/m. The tension in the thread and the angle it makes with the vertical are _____ and _____ respectively.

(a)	9°1', 2.2 × 10^-4 N
(b)	27°3', 8.8 × 10^-4 N
(c)	18°2', 4.4 × 10⁴ N
(d)	27°3', 6.6 × 10^-4 N

138.

A large sheet carries uniform surface charge density σ. A rod of length 2l has a linear charge density λ on one half and -λ on the other half. The rod is hinged at midpoint O and makes an angle of θ with the normal to the sheet. The torque experienced by the rod is _____.

(a)	$\frac{σλ l^{2}}{2 ε_{0}} \sin θ$
(b)	$\frac{σλ l^{2}}{2 ε_{0}} \cos θ$
(c)	$\frac{σλ l^{2}}{ε_{0}} \sin^{2} θ$
(d)	$\frac{σλ l^{2}}{ε_{0}} \cos^{2} θ$

139.

Two point charges placed at a distance of 0.2 m in air repel each other with a certain force. When a dielectric slab of thickness 0.08 m and dielectric constant K is introduced between the point charges, the force acting between them becomes half. The value of K is _____.

(a)	1
(b)	2
(c)	$\sqrt{2}$
(d)	4

140.

P, Q, R, S corners of a square are occupied by q, -q, 2Q and Q charges respectively. The side of square is 2a. The field at the mid point of side RS is zero. What is the value of

\frac{q}{Q}

(a)	$\frac{5 \sqrt{5}}{2}$
(b)	$\frac{2 \sqrt{2}}{5}$
(c)	$\frac{2}{5}$
(d)	$\frac{5}{2}$

Showing 131 to 140 out of 141 Questions