Several questions about the direction of induced current In

Several questions about the direction of induced current. In all the parts of this question, the same initial situation holds, shown in the figure. In the heavy loop there is a clockwise current. Something about the arrangement is changing, and a current may or may not be induced in the lighter loop as a result. For each part, specify whether the induced current runs clockwise, counterclockwise, or if no current is induced at all. The current in the heavy loop is increased, The heavy loop is pulled away to the left, The heavy loop is rotated: its top side is lifted and the bottom is sunk so that the loop lies in a plane perpendicular to the page, and the current is coming out of the page at the left, running over the top from left to right, and diving into the page on the right, The heavy loop is cut so the current stops flowing, The heavy loop and its current is unchanged, but the lighter loop is crushed so it becomes smaller in diameter.

Solution

According to the direction of current shown in the figure, magnetic field for the heavy loop will be pointing towards left. As we know from the Len\'z law accordingly field will be setup in the near by conducting coil/ loop and changing flux will produce resisting EMF in the loop.

As it is being said that the coil current is heavyly increased, it menas flux is changing.

a) As flux is increasing changing EMF will try to resist in the nearby loop which will results into magnetic field opposite to heavy loop that is towards right, which will give current in counter clockwise direction.

b) If heavy loop is pulled away, direction of B (magnetic field) will be towards left, as it moved away it will change the magnetic field in the nearby loop which means the direction of magnetic field in lighter loop will reverse and comes to be pointing towards left which will reverse the induced current direction. Clockwise current direction.

c) if we bring the heavy loop as per the directions given in c, magnetic field for the heavy loop will change which will in result change field direction in lighter loop (apply right hand tumb rule). Opposite magnetic field will setup the lighter loop resulting into clock wise current direction in lighter loop.

d) if there is no current flowing, which will result into no change in flux and there will be no incuded current in the lighter loop and the induced current is a result of changing flux

e) induced current is indepentent of the diameter of the loop so it doesn\'t matter if we crush the loop in smaller loops only thing matter will be the changing flux and the resisting EMF to describe the direction of the induced current.

If we know the direction of B, by applying the thumb rule we can know the direction of the current.