NEET UG Physics Magnetic Effects of Electric Current MCQs

129. The coercivity of a bar magnet is 100 A/m. It is to be demagnetised by placing it inside a solenoid of length 100 cm and number of turms 50. The current flowing through the solenoid will be
(a) 4 A
(b) 2 A
(c) 1 A
(d) Zero

130. The angles of dip at two places are 300 and 450. The ratio of horizontal components of earth's magnetic field at the two places will be
(a) 3 : 2
(b) 1 : 2
(c) 1 : 2
(d) 1 : 3

ASSERTION - REASON TYPE

Read the assertion and reason carefully to mark the correct option out of the options given below.
(A) If both assertion and reason are true and the reason is the correct explanation of the asseration.
(B) If both assertion and reason are true but reason is not the correct explaination of the asseration,
(C) If assertion is true but reason is false.
(D) If the assertion and reason both the false.
(E) If assertion is false but reason is true.

131. Assertion : We cannot think of magnetic field configuration with three poles.
Reason : A bar magnet does exert a torque on itself due to its own field.    

132. Assertion : If a compass needle be kept at magnetic north pole of the earth, the compass needle may stay in any direction.
Reason : Dip needle will stay vertical at the north pole.

133. Assertion : Dia-magnetic materials can exhibit magnetism.
Reason : Dia-magnetic materials have permanent magnetic dipole moment.

134. Assertion : A paramagnetic sample displays greater magnetisation when it is cooled.
Reason : The magnetisaution does not depend on temperature.