Physics

Magnetism and Electromagnetism

1,019 Questions

This hub provides practice questions on magnetism and electromagnetism. It covers magnetic flux density, electromagnets, magnetic lines of force, and electromagnetic induction. These physics concepts frequently appear in technical and non-technical competitive exams.

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Magnetism and Electromagnetism Questions

Multiple choice physics applications of electromagnets

When the current through the electromagnet of a relay reaches a particular value.

  1. It breaks the circuit

  2. It opens the circuit by pulling in an iron contact

  3. It closes the circuit by pulling in an iron contact

  4. Both A or C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A relay is an electromagnetic switch. Depending on the design, the movement of the iron contact can either open or close a secondary circuit when the electromagnet is energized.

Multiple choice properties of magnet magnetism physics neutral points magnetic poles and magnetic compass magnetic field

A magnetic needle is kept in a nonuniform magnetic field. It

  1. may experience a force but certainly not a torque

  2. may experience a torque but certainly not a force

  3. may experience both a torque as well as force

  4. will certainly experience neither a force not a torque
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If magnet is placed parallel to the magnetic field then two poles of magnetic will experience different forces because of non uniform magnetic field. The forces will be in opposite direction therefore, there will be a net force also because forces are not equal. 
Now , when magnetic is not parallel to the magnetic field it will experience torque its a dipole placed in a field. Hence, (C)

Multiple choice properties of magnet magnetism physics neutral points magnetic poles and magnetic compass magnetic field

The needle of a dip circle when place at a geomagnetic pole stays along

  1. south-north direction only

  2. east-west direction only

  3. vertical direction

  4. horizontal direction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Dip is the angle between the Earth's magnetic field and horizontal plane at that point. The needle of a dip circle when place at a geomagnetic poles stays along vertical direction.

Multiple choice motional emf physics

A magnet is brought towards a coil (i) speedly (ii) slowly, then the induced electromotive force charge will be respectively

  1. More in first case / More in first case

  2. More in first case / Equal in both case

  3. Less in first case / More in second case

  4. Less in first case / Equal in both case
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Induced EMF is proportional to the rate of change of magnetic flux (dPhi/dt). Moving the magnet speedily increases the rate of change, resulting in a higher induced EMF. However, the total charge induced (q = delta Phi / R) depends only on the total change in flux, which is the same regardless of speed.

Multiple choice

Every magnet has a north and south pole.

  1. true

  2. false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

All magnets have two poles, a north pole and a south pole, where the magnetic force is strongest. Even if you cut a magnet in half, each piece will still have a north and south pole.

Multiple choice

What type of magnet is our Earth like?

  1. bar magnet

  2. electromagnet

  3. temporary magnet

  4. donut magnet
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Earth acts like a giant bar magnet because of the movement of molten iron in its outer core, which creates a magnetic field with north and south poles.