Answer:
(i)
Activity:
(a) Take a coil of wire AB
having a large number of turns.
(b) Connect the ends of the
coil to a galvanometer.
(c) Take a strong bar magnet
and move its north pole towards the end B of the coil.
(d) There is a momentary
deflection in the needle of the galvanometer, say to the right. This indicates
the presence of a current in the coil AB. The deflection becomes zero the
moment the motion of the magnet stops.
(e) Now withdraw the north
pole of the magnet away from the coil. Now the galvanometer is deflected toward
the left, showing that the current is now set up in the direction opposite to
the first.
(f) Place the magnet
stationary at a point near to the coil, keeping its north pole towards the end
B of the coil. We see that the galvanometer needle deflects toward the right
when the coil is moved towards the north pole of the magnet. Similarly, the
needle moves toward left when the coil is moved away.
When the coil is kept
stationary with respect to the magnet, the deflection of the galvanometer drops
to zero.
To find the direction of
electric current Fleming's right hand rule is applied. According to it, if we
stretch the forefinger, middle finger and thumb of our right hand mutually
perpendicular in such a way that thumb points along the direction of motion of
conductor, forefinger along the direction of magnetic field; then the middle
finger points along the direction of induced current.
(ii) (a) When current in P is
changed, the field associated with Q will vary causing an induced current in Q.
(b) If both the coils are
moved in the same direction with same speed, there will not be any change in
the field associated with Q. Hence no current will be induced in Q.
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