in this example. we are given that in figure
shown, a coil of area ay and n turns with
a current i is placed in a uniform magnetic
induction b. and we are required to find the
work required to pull this coil out of the
magnetic field. now in the solution. we can
see. that work done. in, any process of changing
the orientation of coil can be given as work
done in. this process. this we can write w
is, minus i delta phi where. i is the current
flowing in the coil and delta phi is the change
in magnetic flux through the coil. which can
be written as i phi 1 minus phi-2 because
delta phi is phi 2 minus phi-1. so if we calculate
the initial flux. through coil. then this
initial flux. phi 1 can be calculated as.
the magnetic induction b dot ay we generally
used multiplied by the number of turns. so
here we can see according to the direction
of current its area vector is in inward direction
which is parallel to b. so it can be written
as b-a coz theta coz zero will be taken as
1 so it’ll be b-a-n. and when the coil is
pulled out of the magnetic field we can write.
final flux through coil which is phi 2 which
can be written as zero. so in this situation
work done can be directly calculated by this
expression is. i multiplied by phi 1 minus
phi-2 which is b -a - n minus zero. so this
can be written as b, i, ay, n. that will be
the answer to this. problem.
