JEE Physics Electric Charges and Fields MCQs Set C

Question:

• a) 2 × 10^–3 N m
• b) 4 × 10^–3 N m
• c) 10^–3 N m
• d) 2 × 10^–4 N m

Answer: 2 × 10^–3 N m

Question: A charge Q is situated at the centre of a cube. The electric flux through one of the faces of the cube is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  A charge q is placed at the centre of the open end of a cylindrical vessel. The flux of the electric field through the surface of the vessel is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) Both
• b) III only
• c) II only
• d) None of these

Answer: Both

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: 4.55 × 10⁵ C

Question: A sphere of radius R has a uniform distribution of electric charge in its volume. At a distance x from its centre for x < R, the electric field is directly proportional to

• a) x
• b)

  

• c)

  

• d) None of these

Answer: x

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: 2 E

Question:

• a) 16F
• b) 8F
• c) 4F
• d) 2F

Answer: 16F

Question:

• a) On the left of –Q
• b) Between –Q and 2Q
• c) On the right of 2Q
• d) On the perpendicular bisector of line joining the charges

Answer: On the left of –Q

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

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: 4 : 1

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: 8.854 × 10^–9 C

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: One

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: Some special symmetric charge configuration

Question: An electric dipole when placed in a uniform electric field E will have minimum potential energy, when the angle made by dipole moment with field E is

• a) Zero
• b)

  

• c)

  

• d) None of these

Answer: Zero

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: All of these

Question: Each of two large conducting parallel plates has one sided surface area A. If one of the plates is given a charge Q whereas the other is neutral, then the electric field at a point in between the plates is given by

• a)

  

• b)

  Zero

• c)

  

• d)

  

Answer:

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: 6.8 × 10⁵ coulomb

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  What is the flux through a cube of side a if a point charge of q is at one of its corner?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

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: Remain the same

Question:

• a) 1.64 × 10^–26 N, 2.4 × 10^–16 N
• b) 1.64 × 10^–26 N, 1.5 × 10³ N
• c) 1.5 × 10³ N, 2.4 × 10^–16 N
• d) 1.56 × 10^–18 N, 2.4 × 10^–16 N

Answer: 1.64 × 10^–26 N, 2.4 × 10^–16 N

Question: The frequency of oscillation of an electric dipole moment having dipole moment p and rotational inertia I, oscillating in a uniform electric field E is given

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

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: –7.5 × 10^–9 C

Question:

• a) E along OK
• b) E along KO
• c) 3 E along KO
• d) 3 E along OK

Answer: E along OK

Question:

• a) Both are negative
• b) Both are positive
• c)

  

• d)

  

Answer: Both are negative

Question: A charge q is placed at the centre of the line joining two exactly equal positive charges Q. The system of three charges will be in equilibrium, if q is equal to

• a)

  

• b)

  

• c)

  

• d)  –Q

Answer:

Question: A point charge +q is placed at the mid-point of a cube of side l. The electric flux emerging from the cube is

• a)

  

• b)

  

• c)

  

• d) Zero

Answer:

Question: A point Q lies on the perpendicular bisector of an electrical dipole of dipole moment p. If the distance of Q from the dipole is r (much larger than the size of the dipole), then the electric field at Q is proportional to

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A particle of mass m and charge q is placed at rest in a uniform electric field E and then released. The kinetic energy attained by the particle after moving a distance y is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) Zero
• b)

  

• c)

  

• d)

  

Answer: Zero

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: Decreases K times

Question: A charge Q is situated at the corner of a cube, the electric flux passed through all the six faces of the cube is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A charge q is located at the centre of a cube. The electric flux through any face of the cube is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) Zero
• b)

  

• c)

  

• d)

  

Answer: Zero

Question:

• a)

  

• b)

  

• c)

  

• d) qa along the line joining points (x = 0, y = 0, z = 0) and (x = a, y = a, z = 0)

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

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• a)

  

• b)

  

• c)

  

• d)

  

Answer: