JEE Physics Electric Charges and Fields MCQs Set 03

Question. If the electric field intensity in a fair weather atmosphere is 100 V/m, then the total charge on the earth’s surface is (radius of the earth is 6400 km)
(a) 4.55 × 10⁵ C
(b) 4.55 × 10⁶ C
(c) 4.55 × 10⁸ C
(d) 4.55 × 10⁷ C

Answer: A

Question. The electric field at 20 cm from the centre of a uniformly charged non-conducting sphere of radius 10 cm is E. Then at a distance 5 cm from the centre it will be
(a) 2 E
(b) Zero
(c) 4 E
(d) 16 E

Answer: A

Question. Two isolated metallic spheres of radii 2 cm and 4 cm are given equal charge, then the ratio of charge density on the surfaces of the spheres will be
(a) 4 : 1
(b) 8 : 1
(c) 1 : 4
(d) 1 : 2

Answer: A

Question. If the number of electric lines of force emerging out of a closed surface is 1000, then the charge enclosed by the surface is
(a) 8.854 × 10^–9 C
(b) 8.854 × 10^–4 C
(c) 8.854 × 10^–1 C
(d) 8.854 C

Answer: A

Question. A charge of 1 coulomb is located at the centre of a sphere of radius 10 cm and a cube of side 20 cm. The ratio of outgoing flux from the sphere and cube will be
(a) One
(b) More than one
(c) Less than one
(d) Nothing certain can be said

Answer: A

Question. Gauss’s law can help in easy calculation of electric field due to
(a) Some special symmetric charge configuration
(b) Any charge configuration
(c) Moving charge only
(d) Any symmetrical charge configuration

Answer: A

Question. An electric dipole is placed in non-uniform electric field. It may experience
(a) All of these
(b) Only resultant force
(c) Resultant force and couple
(d) Only couple

Answer: A

Question. If atmospheric electric field is approximately 150 volt/m and radius of the earth is 6400 km, then the total charge on the earth’s surface is
(a) 6.8 × 10⁵ coulomb
(b) 6.8 × 10⁶ coulomb
(c) None of these
(d) 6.8 × 10⁴ coulomb

Answer: A

Question. A charge Q is enclosed by a Gaussian spherical surface of radius R. If the radius is doubled, then the outward electric flux will
(a) Remain the same
(b) Be reduced to half
(c) Increase four times
(d) Be doubled

Answer: A

Question. What is the net charge on a conducting sphere of radius 10 cm? Given that the electric field 15 cm from the center of the sphere is equal to 3 × 10³ N/C and is directed inward
(a) –7.5 × 10^–9 C
(b) 7.5 × 10^–5 C
(c) 7.5 × 10^–9 C
(d) –7.5 × 10^–5 C

Answer: C

Question. When air is replaced by a dielectric medium of constant K, the maximum force of attraction between twocharges separated by a distance
(a) Decreases K times
(b) Remains unchanged
(c) Increases K times
(d) Increases K^–2 times

Answer: A