Physics Class 12 NCERT Solutions: Chapter 6 Electromagnetic Induction Part 1

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Direction of current and magnetic field: Lenz's law

Direction of Current and Magnetic Field: Lenz's Law

Direction of current and magnetic field: Lenz's law

Q: 1. Predict the direction of induced in the situations described by the following figures (a) to (f).

(A)

Q 1 A The Direction of Induced in the SItuations

Q 1 a the Direction of Induced in the SItuations

Q 1 A The Direction of Induced in the SItuations

(B)

Q 1 B The Direction of Induced in the SItuations

Q 1 B the Direction of Induced in the SItuations

Q 1 B The Direction of Induced in the SItuations

(C)

Q 1 C The Direction of Induced in the SItuations

Q 1 C the Direction of Induced in the SItuations

Q 1 C The Direction of Induced in the SItuations

(D)

Q 1 D The Direction of Induced in the SItuations

Q 1 D the Direction of Induced in the SItuations

Q 1 D The Direction of Induced in the SItuations

(E)

Q 1 E The Direction of Induced in the SItuations

Q 1 E the Direction of Induced in the SItuations

Q 1 E The Direction of Induced in the SItuations

(F)

Q 1 F The Direction of Induced in the SItuations

Q 1 F the Direction of Induced in the SItuations

Q 1 F The Direction of Induced in the SItuations

Answer:

The direction of the induced current in a closed loop is given by Lenz’s law. The given pairs of figures the direction of the induced current when the North pole of a bar magnet is moved towards and away from a closed loop respectively.

Q 1 The Direction of the Induced in the given situation

Q 1 the Direction of the Induced in the Given Situation

Q 1 The Direction of the Induced in the given situation

Using Lenz’s rule, the direction of the induced current in the given situations can be predicted as follows:

(A) The direction of the induced current is along

(B) The direction of the induced current is along .

(C) The direction of the induced current is along .

(C) The direction of the induced current is along .

(E) The direction of the induced current is along .

(F) No current is induced since the field lines are lying in the plane of the closed loop.

Q: 2. A long metallic rod is rotated with an angular frequency of about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field of parallel to the axis exists everywhere. Calculate. The emf developed between the centre and the ring.

Answer:

Length of the rod,

Angular frequency,

Magnetic field strength,

One end of the rod has zero linear velocity, while the other end has a linear velocity of .

Average linear velocity of the rod,

Emf developed between the centre and the ring,

Hence, the emf developed between the centre and the ring is .