MCQs of Electric Charges and Electric Fields

Electric Charges and Electric Fields MCQs

MCQs of Electric Charges and Electric Fields

Showing 21 to 30 out of 141 Questions

21.

Two small, identical spheres, one positively charged and another negatively charges are placed 0.5 m apart attract each other with a force of 0.108 N. if they are brought in contact for some time and again separated by 0.5 m, they repelled each other with force of 0.036 N. What were the initial charges on the spheres ?

(a)	q₁ = 3.0 × 10^-6 C, q₂ = 3.0 × 10^-6 C
(b)	q₁ = 1.0 × 10^-7 C, q₂ = 3.0 × 10^-6 C
(c)	q₁ = 3.0 × 10^-6 C, q₂ = 1.0 × 10^-6 C
(d)	q₁ = 1.0 × 10^-6 C, q₂ = 1.0 × 10^-6 C

22.

Two identical metal spheres A and B carry same charge q. When the two spheres are at a distance r from each other, the force acting between them is F. another identical uncharged sphere c is first brought in contact with A , then it is touched to sphere B and then separated from it. Now, the force acting between A and B at the same distance is _____ .

(a)	F
(b)	2A
(c)	$\frac{3 F}{8}$
(d)	$\frac{F}{4}$

23.

A charge of 4 × 10^-8 C is uniformly distributed over the surface of sphere of radius 1 cm. Another hollow sphere of radius 5 cm is concentric with the smaller sphere. The intensity of the electric filed at a distance 2 cm from the centre is _____ k = 9 × 10⁹ SI.

(a)	4 × 10^-5 NC^-1
(b)	9 × 10³ NC^-1
(c)	4 × 10⁵ NC^-1
(d)	9 × 10⁵ NC^-1

24.

A particle of mass 5 × 10^-9 kg is held at some distance from very large uniformly charged plane. The surface charge density on the plane is 4 × 10^-6 C/m². What should be the charge on the particle so that the particle remains stationary even after releasing it ?(ε₀ = 8.85 × 10^-12 C^-2N^-1m^-2 and g = 9.8ms^-2)

(a)	2.17 × 10^-15 C
(b)	2.17 × 10^-14 C
(c)	2.17 × 10^-13 C
(d)	2.17 × 10^-12 C

25.

In the hydrogen atom, an electron revolves around a proton in a circular orbit of radius 0.53 Å. The radial accele-ration and the angular velocity of the electron are _____ and _____ (m_e = 9.1 × 10^-31 kg, e = 1.6 × 10^-19C)

(a)	0.9 × 10²³ ms^-2, 4.1 × 10¹⁶ rad/s
(b)	9.0 × 10²³ ms^-2, 4.1 × 10¹⁶ rad/s
(c)	0.9 × 10²³ ms^-2, 4.1 × 10¹⁷ rad/s
(d)	9.0 × 10²³ ms^-2, 4.1 × 10¹⁷ rad/s

26.

Two point charges q and 4q are kept 30 cm apart. At a distance _____, on the straight line joining them, the intensity of electric field is zero.

(a)	20 cm from 4q
(b)	7.5 cm from q
(c)	15 cm from 4q
(d)	5 cm from q

27.

The dimensions of permittivity

[ε_{0}]

are _____ . Take Q as the dimensions of charge.

(a)	$M^{1} L^{- 2} T^{- 2} Q^{- 2}$
(b)	$M^{- 1} L^{2} T^{3} Q^{- 1}$
(c)	$M^{- 1} L^{- 3} T^{2} Q^{2}$
(d)	$M^{- 1} L^{3} T^{- 2} Q^{- 2}$

28.

There exists an electric field of 100 N/C along Z-direction. The flux passing through a square of 10 cm sides placed on xy plane inside the electric field is _____ .

(a)	1.0 N m²/C
(b)	2.0 V m
(c)	10 V m
(d)	4.0 N m²/C

29.

The radius of a conducting spherical shell is 10 mm and a 100 µC charge is spread on it. The force acting on a 10 µC charge placed at its centre is _____ .(k = 9 × 10⁹ MKS)

(a)	10³ N
(b)	10² N
(c)	zero
(d)	10⁵ N

30.

Two spheres carrying charge q are hanging from the same point of suspension with the help of threads of length 1 m, in a space free from gravity. The distance between them will be _____ .

(a)	0
(b)	0.5
(c)	2 m
(d)	can not be determined

Showing 21 to 30 out of 141 Questions