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प्रश्न
Establish the fact that the relative motion between the coil and the magnet induces an emf in the coil of a closed circuit.
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उत्तर
- In first experiment when bar magnet is placed close to the coil, magnetic lines pass through coil, the magnetic flux in coil increases and emf is induced hence electric current flows in the circuit.
- At the same time when they recede away from one another magnetic flux decreases emf is induced in opposite direction. Current flows in opposite direction. So there is a deflection in the galvanometer.
- In the second experiment, when the primary circuit is open, no electric current flows in it, magnetic flux linked with the secondary coil is zero.
(a) Right deflection - When primary circuit is closed, increasing current produces a magnetic field. So magnetic flux linked with coil increases. This induced current in the secondary coil.
(a) Left deflection - When the primary circuit is broken, decreasing primary current induces a current in the secondary coil but in opposite direction. So there is a deflection in Galvanorneter.
(a)
(b)
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संबंधित प्रश्न
When a bar magnet is pushed towards (or away) from the coil connected to a galvanometer, the pointer in the galvanometer deflects. Identify the phenomenon causing this deflection and write the factors on which the amount and direction of the deflection depends. State the laws describing this phenomenon.
Name two devices in which electromagnets are used and two devices where permanent magnets are used.
Describe different ways to induce current in a coil of wire.
Figure shows a wire sliding on two parallel, conducting rails placed at a separation l. A magnetic field B exists in a direction perpendicular to the plane of the rails. What force is necessary to keep the wire moving at a constant velocity v?
A transformer has 400 turns in the primary winding and 10 turns in the secondary winding. The primary e.m.f. is 250 V and the primary current is 2.0 A. calculate:
(a) The secondary voltage,
(b) The secondary current, assuming 100% efficiency.
Fleming's left hand rule : electric current : : Fleming's right hand rule : _______
The condition for the praenomen of electromagnetic induction is that there must be a relative motion between ____________.
Induced current flows through a coil ______.
AB is a coil of copper wire having a large number of turns. The ends of the coil are connected with a galvanometer as shown. When the north pole of a strong bar magnet is moved towards end B of the coil, a deflection is observed in the galvanometer.
- State the reason for using galvanometer in the activity and why does its needle deflects momentarily when magnet is moved towards the coil.
- What would be observed in the galvanometer in a situation when the coil and the bar magnet both move with the same speed in the same direction? Justify your answer.
- State the conclusion that can be drawn from this activity.
Will there be any change in the momentary deflection in the galvanometer if number of turns in the coil is increased and a more stronger magnet is moved towards the coil?
OR
What is electromagnetic induction? What is observed in the galvanometer when a strong bar magnet is held stationary near one end of a coil of large number of turns? Justify your answer.
