Assertion (A) : Magnetic field lines never intersect each other.

Reason (R) : At a particular point, magnetic field has only one direction.

1. both A and R are true and R is the correct explanation of A
2. both A and R are true and R is not the correct explanation of A
3. assertion is false but reason is true
4. assertion is true but reason is false

Assertion (A) : Neutral points are the points at which two magnetic fields are equal in magnitude and in the same direction.

Reason (R) : The net magnetic field at a neutral point is zero.

1. both A and R are true and R is the correct explanation of A
2. both A and R are true and R is not the correct explanation of A
3. assertion is false but reason is true
4. assertion is true but reason is false

Name the material used for preparing an electromagnet.

A coil of insulated copper wire is wound around a piece of soft iron and current is passed in the coil from a battery. What name is given to the device so obtained? Give one use of the device mentioned by you.