NEET (UG)

Practice Test 1 — Magnetism & Matter

12 questions • 18 minutes • auto-graded with full solutions

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Section A — MCQ (Single Correct)

Question 1

Magnetic field lines of a bar magnet are:

Solution: No monopoles, so lines form closed loops.

Question 2

The field of a magnetic dipole on its axis varies as:

Solution: Dipole field $\propto 1/r^3$.

Question 3

The angle of dip at the magnetic poles is:

Solution: Needle is vertical, dip $= 90^{\circ}$.

Question 4

The horizontal component of Earth's field is $B_H = B\cos I$, where $I$ is the:

Solution: $I$ is the angle of dip.

Question 5

Relative permeability equals:

Solution: $\mu_r = 1 + \chi_m$.

Question 6

A material weakly repelled by a magnetic field is:

Solution: Diamagnets are weakly repelled (negative $\chi_m$).

Question 7

Curie's law for a paramagnet states $\chi$ is proportional to:

Solution: $\chi \propto 1/T$.

Question 8

The reverse field needed to demagnetise a material is its:

Solution: Coercivity is the demagnetising reverse field.

Section B — Assertion & Reason

Question 9

A: An isolated magnetic north pole cannot exist.
R: Magnetic field lines always form continuous closed loops.

Solution: No monopoles is exactly why field lines close on themselves — R explains A.

Question 10

A: A ferromagnetic material loses its strong magnetism above the Curie temperature.
R: Thermal agitation destroys the alignment of domains at high temperature.

Solution: Loss of domain alignment is the cause of losing ferromagnetism — R explains A.

Question 11

A: The susceptibility of a paramagnetic material increases as temperature rises.
R: By Curie's law, susceptibility is inversely proportional to absolute temperature.

Solution: By Curie's law susceptibility falls as $T$ rises, so A is false; R correctly states $\chi \propto 1/T$.

Question 12

A: Soft iron with a narrow hysteresis loop is preferred for transformer cores.
R: A narrow loop means less energy is dissipated per magnetisation cycle.

Solution: Low hysteresis loss (narrow loop) is exactly why soft iron suits cores — R explains A.