# Basic Electrical Engineering Questions and Answers – Magnetic Field

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This set of Basic Electrical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Magnetic Field”.

1. What is the magnetic field outside a solenoid?
a) Infinity
b) Half the value of the field inside
c) Double the value of the field inside
d) Zero

Explanation: There are no magnetic lines of force outside a solenoid, hence the magnetic field outside a solenoid is zero.

2. Which, among the following qualities, is not affected by the magnetic field?
a) Moving charge
b) Change in magnetic flux
c) Current flowing in a conductor
d) Stationary charge

Explanation: A stationary charge is not affected by a magnetic field because stationary charges do not have any velocity. Magnetic field cannot occur in a particle having zero velocity.

3. When a charged particle moves at right angles to the magnetic field, the variable quantity is?
a) Momentum
b) Speed
c) Energy
d) Moment of inertia

Explanation: When a charged particle moves perpendicular to the field, its speed remains the same whereas its velocity keeps on changing. Momentum is the product of the mass of the particle and the velocity if the particle, hence since velocity varies, momentum also varies.
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4. 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

Explanation: 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.

5. 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

Explanation: 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.

6. What is the strength of magnetic field known as ________
a) Flux
b) Density
c) Magnetic strength
d) Magnetic flux density

Explanation: Strength of magnetic field is also known as magnetic flux density. It is the amount of magnetic field lines crossing unit area.

7. Weakest force in nature is?
a) Electric force
b) Gravitational force
c) Weak force
d) Magnetic force

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

8. How can a magnetic field be produced?
a) Using a permanent magnet
b) Electric current
c) Using a temporary magnet
d) Using a permanent magnet or electric current

Explanation: An electric current as well as the permanent magnet produces a magnetic field whereas a temporary magnet fails to do so.

9. Can we see magnetic flux lines?
a) Yes
b) No
c) Depends on the strength of the field
d) Only when the field strength is very large

Explanation: No, we cannot see magnetic flux lines as the “lines of magnetic flux” is purely an imaginary concept to understand the magnetic field clearly.

10. Magnetic Field lines move from _______
a) North to south
b) South to north
c) West to east
d) East to west

Explanation: Magnetic field lines originate at the north pole and terminate at the south pole of the magnet.

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