The direction of induced emf is given by lenz law which states that direction of induced emf is such that it oppose the cause which is producing it.
case a :
- a coil is placed near wire in which I is increasing which implies that it produce variable B around it. Due to which magnetic flux around coil changes an emf induced in coil . The direction of B around coil is in outward direction by right hand rule.
- Now, emf induced in coil due to B increasing in outward direction , for opposition of that , direction of induced current it oppose it.
- Hence , current induced in clockwise direction .
case b :
- a coil is placed near wire in which I is decreasing which implies that it produce variable B around it. Due to which magnetic flux around coil changes an emf induced in coil . The direction of B around coil is in outward direction by right hand rule.
- Now, emf induced in coil due to B decreasing in outward direction , for opposition of that , direction of induced current it oppose it.
- Hence , current induced in anticlockwise direction .
case c :
It is quite similar to case b , current induced in clockwise direction.
case d :
No emf induced in a coil , as I is constant which implies that B , Φ is constant . if Φ is constant no emf induced in coil as per faraday law.