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Electromagnetic induction, often known as induction, is a process in which a conductor is placed in a specific position while the magnetic field is constantly changing, or in which the magnetic field is stationary while the conductor is moving. Voltage and EMF (Electromotive Force) are generated across the electrical conductor as a result of this process.
An electric current that regularly reverses direction and changes its amplitude constantly with time is known as alternating current. This is in contrast to direct current, which only travels in one direction and does not change its magnitude.
How do you quadruple the energy stored in an inductor?
By making the current double
Cannot be done
By making the Inductance double
By making the current 2 time the initial current.
Answer: Correct option will be (a) By making the current double.
An emf is induced in an electric circuit whenever the magnetic flux associated with it changes. This is known as:
electromagnetic induction
Lenz’s law
Hysteresis loss
Kirchhoff’s law
Answer: The correct option will be: (a) Electromagnetic induction.
The induced charge in electromagnetic induction is independent of
flux change
time
coil resistance
none of the above
Answer: Correct option will be: (b) time.
When a magnet is inserted into a coil, an induced e.m.f. is generated. The strength of the induced e.m.f. is unaffected by:
the magnet’s strength
the number of turns in the coil
the resistivity of the coil wire
the speed with which the magnet is moved.
Answer: The correct option will be (c)The resistivity of the coil.
A battery is connected to a coil of insulated wire. The pointer of the galvanometer is deflected if it is taken to it because
an induced current is produced
the coil acts as a magnet
the number of turns in the galvanometer’s coil is changed
None of these are true.
Answer: Correct option will be: (a) an induced current is produced.
The polarity of the induced emf is determined by:
Ampere’s circuital law
Biot- savart law
Lenz’s law
Fleming’s right-hand rule
Answer: Correct option will be: (c) Lenz’s law
To counteract the effects of______ resistance boxes’ coils are made of doubled insulated wire.
Heating
Magnetism
Pressure
Self-induced e.m.f.
Answer: Correct option will be: (d) Self-induced e.m.f.
The self-inductance of two pure inductors is L. What will be the net inductance if the inductors are connected in series?
L
2L
L/2
L/4
Answer: Correct option will be: (b)2L
The laws of electromagnetic induction were used to build
Galvanometer
Voltmeter
Electric motor
Generator
Answer: Correct option will be: (d)Generator.
Two coils are placed near each other. The mutual inductance of the two coils is determined by
the rate at which the currents in the two coils change
the position and orientation of two coils in relation to one another.
the material of the coils’ wires.
the currents flowing through the two coils
Answer: Correct option will be: (b) the position and orientation of two coils in relation to one another.
A current i is carried by two identical coaxial circular loops, each circulating in the same direction. When the loops get close enough, you’ll notice that the current in
each increase
each decrease
each stays the same
one increases while the other decreases.
Answer: Correct option will be (b) each decrease.
The flux of the two identical coaxial circular loops adds because they each carry a current circulating in the same direction. The total flux linkage increases as the two are brought closer together. A current will be induced in both loops by Lenz’s law, which will oppose this change in flux. As the flux rises, the current in each loop falls in order to counteract the rising flux.
Average voltage of 50 V is produced when current in a coil changes from 5 A to 2 A in 0.1 s. The coil’s self-inductance is
1.67H
1H
6H
0.67H
Answer: Correct option will be: (a)1.67H
ε=-LdIdt
🡺L=-εdtdI
🡺L=-50×0.12-5
🡺L=1.67H
Two identical coaxial coils P and Q are brought closer together, each carrying an equal amount of current in the same direction. The current
The current increases in P while decreasing in Q
Q increases while decreasing in P
both P and Q increase
both P and Q decrease
Answer: Correct option will be: (d) both P and Q decreases.
Which of the statements below is incorrect?
An emf is induced in a circuit whenever the amount of magnetic flux connected to it changes.
The induced emf persists for as long as the magnetic flux changes.
The conservation of momentum is a consequence of Lenz’s law.
Lenz’s law determines the direction of induced emf.
Answer: Correct option will be (c) The conservation of momentum is a consequence of Lenz’s law.
A solenoid is connected to a battery and receives a constant current. The current will___ if an iron core is inserted into the solenoid.
Increase
decrease
remain the same
first increase then decrease
Answer: Correct option will be: (b)decrease.
Determine which statement is incorrect.
In a steady magnetic field, eddy currents are produced.
By using laminated core, eddy currents can be reduced.
Eddy current is used to generate heat in an induction furnace.
In moving trains, eddy current can be used to generate braking force.
Answer: Correct option will be: (a) In a steady magnetic field, eddy currents are produced.
From 220 V mains, a transformer is used to light a 100 W and 110 V lamp. If the main current is 0.5 amps, then the transformer’s efficiency is:
11%
50%
80%
90%
Answer: Correct option will be: (d)90%
efficiency=power output/power input×100%
=100/220×0.5×100 %
=90%
When the number of turns in the primary and secondary coils are increased to two times each, the mutual inductance
increases to four times
increases to two times
increases to four times
does not change
Answer: Correct option will be: (a)increase to four times.
19. The induced emf is equal to___ when the rate of change of current is unity.
coil thickness
number of turns in coil
coefficient of self-inductance
total flux linked with coil
Answer: Correct option will be: (c) Coefficient of self-inductance.
