Answer:
(a) (i) Ampere's Right-Hand
Thumb Rule If current is passing through a conductor in the direction of thumb
of the right hand, then, the direction of magnetic field is given by that of
curvature of fingers. (1)
(ii) Fleming's Left-Hand
Rule If the forefinger, centre finger and thumb of left hand are stretched
mutually perpendicular are forefinger points in the direction of magnetic
field, centre finger points in the direction of flow of electric current, then
thumb points in the direction offeree acting on the conductor. (1)
(iii) Fleming's Right-Hand Rule
If the forefinger, centre finger and thumb of right hand are stretched mutually
perpendicular and forefinger points in direction of magnetic field, thumb
points in the direction of motion of conductor, then centre finger points in
the direction of induced current. (1)
(b) (i) On doubling the
magnitude of the current, magnetic force gets doubled. (1)
(ii) On reversing the direction
of current, direction of force gets reversed. (1)
Or
The substances, which get
attracted by a magnet are magnetic substances, e.g., iron, nickel.
The substances which are not
attracted by magnet are non-magnetic substances, e.g., aluminium,
copper.
Permanent magnets are made of an
alloy of iron, nickel and chromium (ainico). Nipermag is also used to make
permanent magnets. (1)
Electric current passing through
a coil of wire produces magnetic field in and around the coil in the similar
manner as bar magnet. (1)
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