Question

In a current-carrying solenoid, the magnetic field direction is given by the right hand rule such that the
A. Encircling fingers indicate the direction of electric current
B. Encircling fingers indicate the direction of magnetic field
C. Extended right thumb will point in the direction of the axial magnetic field
D. Both (B) and (C)

Answer 1

Hint:- According to the question, we should go through the whole concept of solenoid which carries the current and also about the magnetic field direction in that particular solenoid.

Complete step by the step solution:-
Solenoid consists of a length of insulated wire coiled into a cylinder shape:
$ * $ Current in solenoid produces a stronger magnetic field inside the solenoid than outside. The field lines in this district are equal and firmly separated indicating the field is exceptionally uniform in strength and course.
$ * $ Field lines outside the solenoid are similar to that of a bar magnet, and it behaves in a similar way – as though it had a north pole toward one side and south pole at the opposite end. Strength of the field reduces with distance from the solenoid.
$ * $ Strength of the magnetic field can be increased by:
increasing the electric current in the coil
increasing the number of coils in the solenoid
using a soft iron core within the solenoid.
$ * $ Reversing the direction of the current reverses the direction of the magnetic field.
 Right-hand rule can be used to find the direction of the magnetic field. In this case, point the wrapped fingers (along the curl) toward the regular current. Then, the thumb will point to the direction of the magnetic field within the solenoid.
 So, in the case of Current-carrying solenoid- encircling fingers indicate the direction of magnetic field and the extended right thumb will point to the direction of magnetic field within the solenoid.

Hence, the correct option is (D.) Both (B) and (C).

Note:- Some applications of solenoid are: in relays, in electric bells, in solenoid valves. Relay is an electromechanical switch (solid state relay being the exception) which is used to drive ac/dc load. With the assistance of hand-off we can drive an air conditioner gear with the assistance of microcontroller. Electromechanical hand-off comprises solenoid.