Magnetic Force Questions

What Is Magnetic Force?

Magnetic force is a basic force that is responsible for the effects such as the working of electric motors, the attraction of magnets for iron etc. Hence, it can be concluded that the magnetic force between two moving charges is the effect in the form of force exerted on a charge by a magnetic field created by another charge.

If a point charge q is placed in the presence of both a magnitude field and an electric field, then the sum of the electric force and the magnetic force acting on the object is the total force on the electric charge q.

Magnetic force is a force that arises due to the interaction of magnetic fields. The magnetic field is a vector quantity, and its unit is tesla, which represents how a moving charge flows around a magnetic object. The magnetic force can be either attractive in nature or a repulsive force.

Magnetic forces exist among moving electric charges, and the magnetic force on a moving charge is exerted in a direction perpendicular to the plane formed by the direction of the surrounding magnetic field and the direction of its velocity.

Important Questions on Magnetic Force

1) Magnetic effect that can be experienced in the space around a current-carrying conductor is called ____.

a) Electric pole

b) Magnetic flux

c) Magnetic field

d) Current

Correct Option: (c)

Explanation: Magnetic field is the space around a current-carrying conductor in which its magnetic effect can be experienced. A conductor modifies the space around when a current is passed through it, and hence it forms a magnetic field.

2) What is the SI unit of the magnetic field?

a) Candela

b) Tesla

c) Weber

d) Ampere

Correct Option: (b)

Explanation: The SI unit of the magnetic field is tesla, and it is a vector quantity.

3) When a stationary charge is placed in a magnetic field, what will be the force exerted by it?

a) Zero

b) Maximum

c) Minimum

d) None of these

Correct Option: (a)

Explanation: A stationary charge does not suffer any interaction against the external magnetic field because it does not produce any magnetic field. Hence, the force exerted is zero.

4) On a moving charged particle, what will be the work done by the magnetic field?

a) Maximum

b) Depends on the strength of the magnetic field

c) Minimum

d) Zero

Correct Option: (d)

Explanation: The work done will be zero because the magnetic force acts in a direction perpendicular to the direction of motion or the direction of the velocity

W = F × dl × cos 90^°

W = 0.

5) What is the force experienced by a magnet at the poles if the north pole of that magnet is brought near a stationary negatively charged conductor?

a) Maximum

b) Depend on the nature of the conductor

c) Zero

d) None of these

Correct Option: (c)

Explanation: Since the stationary charge does not produce any magnetic field, the north pole of the magnet will not experience any force. Hence, zero force will be experienced by the magnet at the poles.

6) Which of the following conditions shows that if a charge moves through a uniform magnetic field, then the force acting on it is maximum?

a) θ = 90^o

b) θ = 100^o

c) θ = 60^o

d) θ = 30^o

Correct Option: (a)

Explanation: F_m is maximum when θ = 90^o, so this is the condition when the force experienced is maximum. This means that the charge experiences a maximum force when it moves at right angle to the direction of the magnetic field.

7) What will be the direction of the force on the charge if it is moving vertically upwards and then enters a region of magnetic field directed towards the north?

a) Up

b) Down

c) Left

d) Right

Correct Option: (c)

Explanation: The magnetic force will act towards the left, according to Fleming’s left-hand rule. The magnetic force will act towards the left when the positive charge enters a region of magnetic field directed towards the north.

8) The magnetic field outside a solenoid will be _____.

a) Double the value of the field inside

b) Infinity

c) Triple the value of the field inside

d) Zero

Correct Option: (d)

Explanation: The magnetic field outside a solenoid will be zero because there are no magnetic lines of force outside a solenoid.

9) Which of the following qualities is not affected by the magnetic field?

a) Change in magnetic flux

b) Current

c) Moving charge

d) Stationary charge

Correct Option: (d)

Explanation: Since the stationary charges do not have any velocity, it is not affected by a magnetic field. A magnetic field cannot happen in a particle which has zero velocity.

10) What will be the variable quantity when a charged particle moves perpendicular to the magnetic field?

a) Momentum

b) Moment of inertia

c) Mass

d) Weight

Correct Option: (a)

Explanation: The speed of the charged particle remains the same, whereas its velocity keeps on changing when it moves at a right angle to the magnetic field. And since the momentum is the product of the mass and the velocity, it means that due to varying velocity, the momentum will be variable too.

Practice Questions

1) What is magnetic flux?

2) Define tesla.

3) Define electromagnetic force.

4) What is Fleming’s left hand rule?

5) What is Faraday’s law of electromagnetic induction?

Suggested Videos

Stay tuned to BYJU’S and Fall in Love with Learning!