MCQs of Electric Charges and Electric Fields

Electric Charges and Electric Fields MCQs

MCQs of Electric Charges and Electric Fields

Showing 121 to 130 out of 141 Questions

121.

The intensity of electric field required to keep a water drop of radius 10^-5 cm suspended in air when charged with one electron is approximately _____.

(a)	130 V/cm
(b)	26 V/m
(c)	130 N/C
(d)	260 N/C

122.

Equal charges q are placed at the vertices A and B of an equilateral triangle ABC of side a. The magnitude of electric field at the point C is _____.

(a)	$\frac{q}{2 π ε_{0} a^{2}}$
(b)	$\frac{\sqrt{2} q}{4 π ε_{0} a^{2}}$
(c)	$\frac{\sqrt{3} q}{4 π ε_{0} a^{2}}$
(d)	$\frac{q}{4 π ε_{0} a^{2}}$

123.

Two equal plates having a potential difference of 800 V are 0.02 m apart horizontally. A particle of mass 1.96 × 10^-15 kg is suspended in equilibrium between the plates. If e is the elementary charge, then the charge on the particle is _____.

(a)	6e
(b)	e
(c)	8e
(d)	3e

124.

Two charges of +5 µC and +10 µC are placed 20 cm apart. The net electric field at the mid-point between the two charges is _____.

(a)	4.5 × 10⁶ N/C directed towards +10 µC
(b)	13.5 × 10⁶ N/C directed towards +5 µC
(c)	13.5 × 10⁶ N/C directed towards +10 µC
(d)	4.5 × 10⁶ N/C directed towards +5 µC

125.

Charges 4Q, q and Q are placed along X-axis at positions x = 0, x =

\frac{1}{2}

, and x = 1. Find the value of q so that force on charge Q is zero.

(a)	-Q
(b)	$- \frac{Q}{2}$
(c)	Q
(d)	$\frac{Q}{2}$

126.

At a point 20 cm from the centre of a uniformly charged dielectric sphere of radius 10 cm, the electric field is 100 V/m. The electric field at 3 cm from the centre of the sphere will be _____.

(a)	125 V/m
(b)	120 V/m
(c)	zero
(d)	150 V/m

127.

An electron moving with a speed of 5 × 10⁶ m/s is shooted parallel to the electric field of intensity 1 × 10³ N/C. Field is responsible for the retardation of motion of electron. Now, evaluate the distance travelled by the electron before coming to rest. (Mass of e = 9.1 × 10^-31 kg)

(a)	0.7 cm
(b)	0.7 mm
(c)	7 m
(d)	7 cm

128.

An infinite line charge produced a field of 7.182 × 10⁸ N/C at a distance of 2 cm. The linear charge density is _____.

(a)	7.98 × 10^-4 C/m
(b)	7.27 × 10^-4 C/m
(c)	7.04 × 10^-4 C/m
(d)	7.11 × 10^-4 C/m

129.

Radius of a charged spherical shell is 0.5 m. Now, imagine spherical surface of radius 2 m and 3 m concentric with spherical shell of 0.5 m radius. If the electric fields on these surfaces are E₁ and E₂ respectively, then _____.

(a)	$E_{1} = \frac{3}{2} E_{2}$
(b)	$E_{2} = \frac{9}{4} E_{1}$
(c)	$E_{1} = \frac{9}{4} E_{2}$
(d)	$E_{1} = E_{2}$

130.

A non-uniform electric field is represented by,

\vec{E} = 5 x \overset{\land}{i}

V/m. An electric dipole having moment of p = 20 × 10^-20 cm is placed at an angle of 60° with the field. The net force on the dipole is _____ N.

(a)	$10^{- 19} \overset{\land}{i}$
(b)	$100 \times 10^{- 19} \overset{\land}{i}$
(c)	zero
(d)	$5 \times 10^{- 19} \overset{\land}{i}$

Showing 121 to 130 out of 141 Questions