Important Questions for Class 12 Physics Chapter 6 Electromagnetic Induction Class 12 Important Questions
Dear students Important Questions for Class 12 Physics Chapter 6 Electromagnetic Induction Class 12 Important Questions have been collected at one place to get you all prepared for your 12th Bihar board exam, as well as for UP board exams ,Jharkhand board exam ,MP board exams ,Rajsthan board exams ,cbse board exams and other board exams. Electromagnetic Induction Class 12 Important Questions Very Short Answer Type. Visit my nawendu classes youtube channel for more help.
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Q.(1)- Lenz's law of electromagnetic induction follows the principle of conservation of energy. Discuss it.
Bihar Board - 2019
OR
Lenz’s
law obeys the law of conservation of energy, How ?
When the north pole of a bar magnet is brought near the coil, then according to Lenz's law the direction of induced current at the near end of the coil is anticlockwise, due to which that end acts like the north pole. Therefore, it opposes bringing the north pole of the bar magnet closed to it.
Then in the same way, when the north pole of the magnet is taken away from the coil, then the direction of the current at the near end of the coil is clockwise. Due to which it acts like the South Pole. And it opposes taking the North Pole away from it.
Similarly, according to Lenz's law, when the south pole of a magnet is brought near or taken away from the coil, the direction of induced current is such that it opposes bringing the south pole of the bar magnet closed to it or taking the south pole away from it.
Therefore, in all the above situations, work has to be done against this opposition to bring the pole of a magnet near a coil or taken away from the coil. And this work is produced in the form of electrical energy in the coil. Therefore, Lenz's law follows the principle of conservation of energy.
Q.(2)- Write Lenz's law of electromagnetic induction.
Bihar Board - 2013 ,2016
Answer- Lenz's law- In the phenomena of electromagnetic induction ,the direction of induced current is such that it opposes the cause which is responsible for its production.
Q.(3)- What do you mean by mutual induction ?
Bihar Board - 2020
Answer- Phenomena of inducing emf and current in the neighboring coil (secondary coil) due to change in current flowing through a coil (primary coil) is called mutual induction.
Q.(4)- Find an expression of self induction of an ideal solenoid.
Bihar Board - 2014
Answer- Read in nawendu classes note
Q.(5)- What do you mean by eddy currents?
Bihar Board - 2013
What are eddy currents? Give its two uses.
Bihar Board - 2018
Answer- When flux linked to a metal plate changes then currents induced in the whole volume of the conductor which are called eddy currents.
Uses of eddy currents-
(i) eddy currents are used for braking high speed trains.
(ii) eddy currents are used in metal detectors.
Q.(6)- In resistance box, resistance coils
are made by doubled wire. Why ?
Answer- Coils of resistance box are made by wrapping
doubled wire on a wooden cylinder due to which current flows in two opposite
directions in these coils. As a result total flux of these coils is zero.
Therefore self induction does not take place hence these coils have only resistance
(except inductance). This is why the coils of resistance box are made by doubled wire.
Q.(7)- Some time it is seen that when electric bulb is suddenly switched off, the bulb is fused?
Answer- When electric bulb is suddenly switched off, the current becomes zero from a maximum value in very short time. So rate of change of flux is very high. So a strong induced current is produced in the direction of main current so filament coil is fused due to heating effect of this high current.
Q.(8)-In Wheatstone bridge first of all, key of battery is pressed then key of galvanometer. Why?
Answer – If key of galvanometer is first pressed then key of battery is pressed then induced current produced in the arms of the Wheatstone bridge, because main current acquires its constant values after some time. Due to which a balanced Wheatstone bridge will be mis-observed as an unbalanced Wheatstone bridge.
So at first key of battery is pressed and when current acquires a constant value then key of galvanometer is pressed.
Q.(9)- Write down faraday's law of electrommagnetic induction.
Bihar Board - 2023
Answer- Read in nawendu classes notes
chapter 1 ELECTRIC CHARGES AND FIELDS short Q-A
chapter 2 ELECTROSTATIC POTENTIAL AND CAPACITANCE short Q-A
chapter 3 CURRENT ELECTRICITY short Q-A
chapter 4 MOVING CHARGES AND MAGNETISM short Q-A
chapter 5 MAGNETISM AND MATTER short Q-A
chapter 7 ALTERNATING CURRENT short Q-A
chapter 8 ELECTROMAGNETIC WAVES short Q-A
chapter 2 ELECTROSTATIC POTENTIAL AND CAPACITANCE short Q-A
chapter 3 CURRENT ELECTRICITY short Q-A
chapter 4 MOVING CHARGES AND MAGNETISM short Q-A
chapter 5 MAGNETISM AND MATTER short Q-A
chapter 7 ALTERNATING CURRENT short Q-A
chapter 8 ELECTROMAGNETIC WAVES short Q-A
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