Give an illustration of determining direction of induced current by using Lenz's law.

Explanation

(i) Consider a uniform magnetic field, with its field lines perpendicular to the plane of the paper and pointing inwards. These field lines are represented by crosses (x) as shown in Figure (a).
(ii) A rectangular metallic frame ABCD is placed in this magnetic field, with its plane perpendicular to the field. The arm AB is movable so that it can slide towards right or left,

(iii) lf the arm AB slides to our right side, the number of field lines (magnetic flux) passing through the frame ABCD increases and a current is induced.
(iv) As suggested by Lenz.s law, the induced current opposes this flux increase and it tries to reduce it by producing another magnetic field pointing outwards ie.. opposite to the existing magnetic field.
(v) .The magnetic lines of this induced field are represented by red-colored circles in the Figure (b). From the direction of the magnetic field thus produced, the direction of the induced current is found to be anti clockwise by using right-hand thumb rule. (vi) The leftward motion of arm AB decreases magnetic flux. .The induced current, this time, produces a magnetic field in the inward direction (red-colored crosses) i.e., in the direction of the existing magnetic field (Figure(c)).
(vii) Therefore, the flux decrease is opposed by the flow of induced current. From this, it is found that induced current flows in clockwise direction.