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प्रश्न
Show that Lenz's law is a consequence of conservation of energy.
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उत्तर
According to Lenz law, the polarity of the induced emf is such that it opposes the change in magnetic flux responsible for its production.
Experiment:
When the bar magnet with its N-pole is moved towards the coil, the induced current produced in coil S opposes the motion of magnet. It will happen so, if the induced current in the coil S produces magnetic field lines from left to right i.e., if the induced current flows through the coil S in clockwise direction (when seen from left).
Lenz Law and Principle of Conservation of Energy
Lenz law is in accordance with the law of conservation of energy. In the above experiment, when N-pole of magnet is moved towards the coil, the right face of the coil acquires North polarity. Thus, work has to be done against the force of repulsion in bringing the magnet closer to the coil.
When N pole of magnet is moved away, South pole develops on the right face of the coil. Therefore, work has to be done against the force of attraction in taking the magnet away from the coil.
This mechanical work in moving the magnet with respect to the coil changes into electrical energy producing induced current. Hence, energy transformation takes place. Hence, we can say that Lenz's law is a consequence of conservation of energy.
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संबंधित प्रश्न
State Lenz's law. Illustrate, by giving an example, how this law helps in predicting the direction of the current in a loop in the presence of a changing magnetic flux.
Predict the direction of induced current in the situation described by the following figure.
Predict the direction of induced current in a metal ring when the ring is moved towards a straight conductor with constant speed v. The conductor is carrying current I in the direction shown in the figure.
Consider the situation shown in figure. If the switch is closed and after some time it is opened again, the closed loop will show ____________ .
A bar magnet is released from rest along the axis of a very long, vertical copper tube. After some time the magnet ____________ .
Explain, with the help of a suitable example, how we can show that Lenz's law is a consequence of the principle of conservation of energy.
Energy dissipate in LCR circuit in
There are two coils A and B as shown in figure. A current starts flowing in B as shown, when A is moved towards B and stops when A stops moving. The current in A is counterclockwise. B is kept stationary when A moves. We can infer that ______.
Same as problem 4 except the coil A is made to rotate about a vertical axis (figure). No current flows in B if A is at rest. The current in coil A, when the current in B (at t = 0) is counterclockwise and the coil A is as shown at this instant, t = 0, is ______.
Consider a metal ring kept on top of a fixed solenoid (say on a carboard) (Figure). The centre of the ring coincides with the axis of the solenoid. If the current is suddenly switched on, the metal ring jumps up. Explain
