A rectangular loop of copper wire of resistance r has width a and length

b. the loop is stationary in a uniform magnetic field. the magnetic field b at time t = 0 seconds is directed into the page as shown below. the uniform magnetic field varies with time t according to the relationship b = b0 cos ω t, where ω and b0 are positive constants and b is positive when the field is directed into the page. the direction of the induced current in the loop when ω t = π 2 , after the magnetic field begins to oscillate is

Explanation:

b = b₀ cos ω t

When t = 0 , magnetic field will be b₀ and positive or directed into the page . This is the maximum value of magnetic field. As times goes ahead , magnetic field decreases so magnetic flux decreases . The induced emf or current will be such that it will  opposes this reduction of magnetic field. Hence , current in clockwise direction will be  generated in the coil which will generate magnetic flux into the paper.

In this way  current will be induced  clockwise.

gets less

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards