Advertisements
Advertisements
Question
Show that Lenz’s law is in accordance with the law of conservation of energy.
Solution
- The truth of Lenz’s law can be established on the basis of the law of conservation of energy.
- According to Lenz’s law, when a magnet is moved either towards or away from a coil, the induced current produced opposes its motion.
- As a result, there will always be a resisting force on the moving magnet.
- Work has to be done by some external agency to move the magnet against this resisting force.
- Here the mechanical energy of the moving magnet is converted into electrical energy which in turn, gets converted into Joule heat in the coil i.e., energy is converted from one form to another.
APPEARS IN
RELATED QUESTIONS
State three ways in which the strength of an electromagnet can be increased.
State the factors on which the strength of an electromagnet depends. How does it depend on these factors?
Describe different ways to induce current in a coil of wire.
Describe one experiment to demonstrate the phenomenon of electromagnetic induction.
Draw and label the diagram of a simple D.C. motor.
(a) Explain the rotation of the coil, giving a reason for your answer.
(b) How can you reverse the direction of rotation of the armature?
(c) How can you increase the speed of rotation of the motor?
Which of the following scientist invented the rule of electromagnetic induction?
If the sun radiates energy at the rate of 3.6 × 1033 ergs/sec the rate at which the sun is loosing mass is given by ______.
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.
Which type of force is experienced by a moving charge in a magnetic field?
