Magnetic Effects (C10)

(a) What are magnetic field lines? How is the direction of magnetic field at a point in a magnetic field determined using field lines?

(b) Two circular coils ‘X’ and ‘Y’ are placed close to each other. If the current in the coil ‘X’ is changed, will some current be induced in the coil ‘Y’? Give reason.

(c) State ‘Fleming’s right hand rule”.

Answer

a) Magnetic field line:

Path along which a hypothetical free north pole would tend to move 

By drawing a tangent on the magnetic field line at that point

b) Yes.

With change in current in the coil X, the magnetic field associated with it also changes around the coil Y placed near it. This change in magnetic field induces a current in the coil Y.

c) Fleming’s right hand rule

Stretch the thumb, forefinger and middle finger of right hand so that they are perpendicular to each other. If the forefinger indicates the direction of the magnetic field and the thumb shows the direction of motion of the conductor, then the middle finger will show the direction of induced current in the conductor.