MCQs of Electric Charges and Electric Fields

Electric Charges and Electric Fields MCQs

MCQs of Electric Charges and Electric Fields

Showing 71 to 80 out of 141 Questions

71.

Two charges +20 μC and -20 μC which constitute the electric dipole, are separated by 1 cm. The electric field at a point on the equatorial line at a distance of 50 cm from the centre of the dipole is _____ .

(a)	1.44 × 10⁴ N C^-1
(b)	2.88 × 10⁴ N C^-1
(c)	4.76 × 10⁴ N C^-1
(d)	6.24 × 10⁴ N C^-1

72.

The electric field intensity, due to a dipole of length 10 cm and having a charge of 500 μC at a point on the axis at a distance of 20 cm from one of the charges in air, is _____ .

(a)	6.25 × 10⁷ N C^-1
(b)	9.28 × 10⁷ N C^-1
(c)	13.5 × 10¹¹ N C^-1
(d)	20.5 × 10⁷ N C^-1

73.

Two small spheres, each of mass 10 gm, are given equal charges of 10^-7 coulomb. The spheres are then suspended from a point by threads of equal length. If the centres of the spheres are at 3 cm distance, then the angle made by the threads with the vertical will be _____ .

(a)	90°
(b)	30°
(c)	60°
(d)	45°

74.

If the inward and outward electric flux from a closed surface are respectively 8 × 10³ and 4 × 10³ units, then the net charge inside the closed surface is _____ .

(a)	-4 × 10³ C
(b)	4 × 10³ C
(c)	$\frac{- 4 \times 10^{3}}{ε_{0}} C$
(d)	$- 4 \times 10^{3} ε_{0} C$

75.

A point charge causes an electric flux of -1.0 × 10³ N m² C^-1 to pass through a spherical Gaussian surface of 10.0 cm radius centre on the charge. If the radius of the Gaussian surface where three times, then how much flux would pass the surface ?

(a)	-3.0 × 10³ N m² C^-1
(b)	-2.0 × 10³ N m² C^-1
(c)	3.0 × 10³ N m² C^-1
(d)	-1.0 × 10³ N m² C^-1

76.

If the uniform surface charge density on the infinite plane sheet is σ, then electric field near the surface will be _____ .

(a)	$\frac{σ}{ε_{0}}$
(b)	$\frac{2 σ}{ε_{0}}$
(c)	$\frac{σ}{2 ε_{0}}$
(d)	$\frac{3 σ}{ε_{0}}$

77.

A stationary charge produces _____ .

(a)	only magnetic field
(b)	only electric field
(c)	both electric field and magnetic field
(d)	none of these fields

78.

An electric dipole coincides on Z-axis and its midpoint is on the origin of the co-ordinate system. The electric field at an axial point at a distance z from origin is

\vec{E}

(z) and the electric field at an equatorial point at a distance y from origin is

\vec{E}

(y) . Here, z = y >> a, so

|\frac{\vec{E} (z)}{\vec{E} (y)}|

= _____ .

(a)	2
(b)	4
(c)	3
(d)	1

79.

Electrical force between two point charges is 200N. If we increase 10% charge on the other, then the electrical force between them for the same distance becomes _____ .

(a)	200 N
(b)	99 N
(c)	198 N
(d)	100 N

80.

If the coulombian force acting between two protons separated by a distance r is F, then what would be the force acting between two alpha particles separated by a distance 2r ?

(a)	2 F
(b)	$\frac{2}{F}$
(c)	3 F
(d)	F

Showing 71 to 80 out of 141 Questions