MCQs of Electric Charges and Electric Fields

Electric Charges and Electric Fields MCQs

MCQs of Electric Charges and Electric Fields

Showing 91 to 100 out of 141 Questions

91.

Two spheres having same radius and mass are suspended by two strings of equal length from the same point, in such a way, that their surfaces touch each other. On depositing charge 4 × 10^-6 on them, they repel each other in such a way that in equilibrium, the angle between their strings becomes 60°. If the distance from the point of suspension to the centre of the sphere is 10 cm. Find the mass of each sphere. (k = 9 × 10⁹ SI and g = 10 ms^-1)

(a)	0.3117 kg
(b)	0.1559 kg
(c)	0.6235 kg
(d)	1.2468 kg

92.

Electric field produced due to an infinitely long straight uniformly charged wire at perpendicular distance of 2 cm is 3 × 10⁸NC^-1. Then linear charge density on the wire is _____ (k = 9 × 10⁹ SI unit)

(a)	333 $\frac{μ C}{m}$
(b)	666 $\frac{μ C}{m}$
(c)	3.33 $\frac{μ C}{m}$
(d)	6.66 $\frac{μ C}{m}$

93.

When 10¹⁹ electrons are removed from a neutral metal plate through some process, the charge on it becomes _____ .

(a)	-1.6 C
(b)	10¹⁹ C
(c)	+1.6 C
(d)	10^-19 C

94.

An inclined plane of length 5.60 m making an angle of 45° with the horizontal is placed in an uniform electric field E = 100 Vm^-1 . A particle of mass 1 kg and charge 10^-2 C is allowed to slide down from rest position from maximum height of slope. If the coefficient of friction is 0.1, the time taken by the particle to reach the bottom is _____ .

(a)	1 s
(b)	1.41 s
(c)	2 s
(d)	None of these

95.

If an electron travelling at a distance of 0.10 m in an electric field of intensity 3200 V/m enters perpendicular to the field with a velocity of 4 × 10⁷ m/s, then what is the deviation in its path ?

(a)	1.76 mm
(b)	17.6 mm
(c)	176 mm
(d)	0.176 mm

96.

Two small spheres, each having the charge +Q, are suspended by insulating threads of length L from hook. If this arrangement is taken in space where there is no gravitational effect, then the angle between the two suspensions and the tension in each other will be _____ .

(a)	$180 °, \frac{k Q^{2}}{2 L^{2}}$
(b)	$90 °, \frac{k Q^{2}}{L^{2}}$
(c)	$180 °, \frac{k Q^{2}}{L^{2}}$
(d)	$180 °, \frac{k Q^{2}}{(2 L)^{2}}$

97.

Two charged particles of equal charges are placed 1 m apart. The initial acceleration of each of them is 1 ms^-2. If the mass of each is 10^-3 gm, then find the charge on each of them.

(a)	$\sqrt{1.1} \times 10^{- 8} C$
(b)	$1.1 \times 10^{- 8} C$
(c)	$11 \times 10^{8} C$
(d)	$\sqrt{2} \times 10^{- 8} C$

98.

Two particles of equal mass m and charge q are placed at a distance of 16 cm. They do not experience any force. The value of

\frac{q}{m}

is _____ .

(a)	1
(b)	$\sqrt{4 π ε_{0} G}$
(c)	$\sqrt{\frac{π ε_{0}}{G}}$
(d)	$\sqrt{\frac{G}{4 π ε_{0}}}$

99.

An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The coulomb force F acting on the electron is _____ .

(a)	$\frac{k e^{2}}{r^{2}} \hat{r}$
(b)	$\frac{- k e^{2}}{r^{3}} \hat{r}$
(c)	$\frac{k e^{2}}{r^{3}} \hat{r}$
(d)	$\frac{- k e^{2}}{r^{3}} \vec{r}$

100.

Two charges placed in air at a distance r exert force F on each other. If the same force acts between the same two charges at a distance r' when placed in a medium of dielectric constant K = 2, then r' = _____ .

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

Showing 91 to 100 out of 141 Questions