Force on current carrying conductor in magnetic field MCQ [Free PDF] – Objective Question Answer for Force on current carrying conductor in magnetic field MCQ Quiz

1. What is the expression for force in a current-carrying conductor?

A. F = K/r^{2}
B. F = Kq/r^{2}
C. F = Kq_{1}q_{2}/r^{2}
D. F = Kq_{1}q_{2}/r

Answer: C

The force in a current-carrying conductor is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.

Hence F = Kq_{1}q_{2}/r^{2},

where K is the constant of proportionality.

2. Force in a conductor is__________ to the product of the charges.

A. Directly proportional
B. Inversely proportional
C. Not related
D. Cannot be determined

Answer: A

The force in a current-carrying conductor is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.

3. Force in a conductor is __________ to the square of the distance between the charges.

A. Directly proportional
B. Inversely proportional
C. Not related
D. Cannot be determined

Answer: B

The force in a current-carrying conductor is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.

4. Calculate the force between two charges having magnitude 3nC and 2nC separated by a distance of 2micro m.

A. 13.5N
B. 13.5kN
C. 1.35N
D. 1.35kN

From the expression:

F = Kq_{1}q_{2}/r^{2}, of Coulomb’s Law

the value of K being 9 × 10^{9},

we get F = 13.5kN.

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5. If the flow of electric current is parallel to the magnetic field, the force will be?

A. Zero
B. Infinity
C. Maximum
D. Half the original value

Answer: A

Force is a cross-product. A cross product involves the sine of the angle between them. If two quantities are parallel to each other, the angle between them is zero. Sin(0) is zero, hence force is zero.

6. The ratio of magnetic force to electric force on a charged particle getting undeflected in a field is ______

A. 1
B. 0
C. 2
D. 4

Answer: A

When a charged particle is undeflected in a field, the magnitude of the magnetic force and electric force acting on the particle is the same, hence the ratio is 1.

7. Weakest force in nature is __________

A. Electric force
B. Gravitational force
C. Weak force
D. Magnetic force

Answer: A
Gravitational force is the weakest force in nature as it does not bind anything strongly with its help.

8. The relation between the direction of force and the direction of the magnetic field is __________

A. Same direction
B. Opposite direction
C. Perpendicular
D. Unrelated

Answer: C

When a conductor carries a certain value of current, the force developed in the conductor, the current in the conductor, and the magnetic field in the conductor are mutually perpendicular to each other.

9. The relation between the direction of current and the direction of the force is ________

A. Same direction
B. Opposite direction
C. Perpendicular
D. Unrelated

Answer: C

When a conductor carries a certain value of current, the force developed in the conductor, the current in the conductor, and the magnetic field in the conductor are mutually perpendicular to each other.

10. Which among the following, is the correct expression for force in a current-carrying conductor if the magnetic field is perpendicular to it?

A. F = Bi
B. F = B^{2}il
C. F = Bil
D. F = Bl^{2}

Answer: C

The correct expression for force in a current-carrying conductor in a magnetic field perpendicular to it is F = Bil, where B is the magnetic field, i is the current in the conductor and l is the length of the conductor.