12th Physics Monthly Test - 1 ( Electromagnetic Induction And Alternating Current )

St. Britto Hr. Sec. School - Madurai

12th Physics Monthly Test - 1 ( Electromagnetic Induction And Alternating Current )-Aug 2020

Time : 2.30 Hours

Part - A

Multiple Choice Question - Answer All Question

If two coils are wound on a soft iron core the mutual induction is
small

very large

infinity

zero
Which of the following cannot be stepped up in a transformer?
input current

input voltage

input power

all

The voltage drop across the resistor in a LCR series circuit is __________________

V_R = IR
V_R = IR₂
V_R = I/R
V_R=R/I

In an a.c generator, the brushes are made of __________

silicon
plastic
carbon
nylon

Th e fl ux linked with a coil at any instant t is given by \(\Phi\)_B =10t²−50t+ 250 . The induced emf at t = 3s is

−190 V
−10 V
10 V
190 V

In a transformer, eddy current loss is minimized by using

laminated core made of muemetal
laminated core made of stelloy
shell type core
thick copper wire

The magnitude of the induced emf in a conductor depends on the

flux density of the magnetic field
amount of flux cut
amount of flux linkages
rate of change of flux

In a transformer, the number of turns in the primary and the secondary are 410 and 1230 respectively. If the current in primary is 6A, then that in the secondary coil is

2 A
18 A
12 A
1 A

A transformer

converts energy
changes voltage
changes current
changes both current and voltage

Eddy current loss is also known as ________ loss.

copper
heat
hysteresis
iron

A power of 11,000 W is transmitted at 220 V. The current through line wires is

50 A
5 A
500 A
0.5 A

An emf of 12V is induced when the current in the coil changes at the rate of 40 A S^-1. The coefficient of self induction of the coil is

0.3 H
0.003 H
30 H
4.8 H

Flux loss can be minimized using ________ core.

laminated
shell-type
perforated
sheet-type

The unit of impedance is ________________

mho-metre^-1
ohm
ohm-metre
mho-metre

RMS value of AC is ___________ times its peak value

0.707
7.07
1.414
14.14

The property of a coil which enables to produce an opposite induced emf in it when the current in the coil changes is called _______________

electromagnetism
self - induction
mutual induction
parallel- induction

Part - B

Generic 2 - Answer All Question

Give any one definition of power factor.

What is the value of power if the circuit is
(i) purely resistive
(ii) Purely inductive or capacitive.

What for an inductor is used? Give some examples.

Draw a graph showing the variation of reactance of
(i) a capacitor and
(ii) an inductor with the frequency of an a.c circuit.

What is meant by wattles current?

What is meant by power transmission?

State the law that gives the polarity of the induced emf.

What are LC oscillations.
What are step-up and step-down transformers?

How will you define Q-factor?

What is phasort

Define power factor?

Explain the use of transformers in long distance transmission of electric power

What do you mean by resonant frequency?

What are phasors?

What is resonant frequency?
Give the principle of AC generator.

Part - C

Generic 3 - Answer All Question

A solenoid of 500 turns is wound on an iron core of relative permeability 800. The length and radius of the solenoid are 40 cm and 3 cm respectively. Calculate the average emf induced in the solenoid if the current in it changes from 0 to 3 A in 0.4 second.
A circular loop of area 5 x 10^-2m² rotates in a uniform magnetic field of 0.2 T. If the loop rotates about its diameter which is perpendicular to the magnetic field as shown in figure. Find the magnetic flux linked with the loop when its plane is
(i) normal to the field
(ii) inclined 60o to the field and
(iii) parallel to the field.

Distinguish between average & rms value of an AC.
Show that Lenz’s law is in accordance with the law of conservation of energy.

How does the capacitive reactance depend on frequency? & What is the reactance of a capacitor at hertz to the study at?

Explain the working of a single-phase AC generator with necessary diagram.

What do you understand by self-inductance of a coil? Give its physical significance.

How will you induce an emf by changing the area enclosed by the coil?

The magnetic flux passes perpendicular to the plane of the circuit and is directed into the paper. If the magnetic flux varies with respect to time as per the following relation: \(\Phi_B\)=(2t³+3t²+8t+5)mWb, what is the magnitude of the induced emf in the loop when t = 3 s? Find out the direction of current through the circuit.

Give and explain the mechanical analogy of LC oscillations by qualitative treatment.

Find out the phase relationship between voltage and current in a pure inductive circuit.

Establish the fact that the relative motion between the coil and the magnet induces an emf in the coil of a closed circuit.

Part - D

Generic 5 - Answer All Question

Elaborate the standard construction details of AC generator.

Explain mechanical analogy ofLC oscillations by quantitative treatment.
The solenoids S₁ and S₂ are wound on an iron-core of relative permeability 900. The area of their cross-section and their length are the same and are 4 cm² and 0.04 m respectively. If the number of turns in S₁ is 200 and that in S₂ is 800, calculate the mutual inductance between the coils. The current in solenoid 1 is increased form 2A to 8A in 0.04 second. Calculate the induced emf in solenoid 2.

The equation for an alternating current is given by i = 77 sin 314t. Find the peak value, frequency, time period and instantaneous value at t = 2 ms.

A closely wound coil of radius 0.02 m is placed perpendicular to the magnetic field. When the magnetic field is changed from 8000 T to 2000 T in 6 s, an emf of 44 V is induced. Calculate the number of turns in the coil.

Derive an expression for the RMS value of AC.

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12th Physics Monthly Test - 1 ( Electromagnetic Induction And Alternating Current )

St. Britto Hr. Sec. School - Madurai

12th Physics Monthly Test - 1 ( Electromagnetic Induction And Alternating Current )-Aug 2020

Part - A

Multiple Choice Question - Answer All Question

If two coils are wound on a soft iron core the mutual induction is

Which of the following cannot be stepped up in a transformer?

The voltage drop across the resistor in a LCR series circuit is __________________

In an a.c generator, the brushes are made of __________

Th e fl ux linked with a coil at any instant t is given by \(\Phi\)B =10t2−50t+ 250 . The induced emf at t = 3s is

In a transformer, eddy current loss is minimized by using

The magnitude of the induced emf in a conductor depends on the

In a transformer, the number of turns in the primary and the secondary are 410 and 1230 respectively. If the current in primary is 6A, then that in the secondary coil is

A transformer

Eddy current loss is also known as ________ loss.

A power of 11,000 W is transmitted at 220 V. The current through line wires is

An emf of 12V is induced when the current in the coil changes at the rate of 40 A S-1. The coefficient of self induction of the coil is

Flux loss can be minimized using ________ core.

The unit of impedance is ________________

RMS value of AC is ___________ times its peak value

The property of a coil which enables to produce an opposite induced emf in it when the current in the coil changes is called _______________

Part - B

Generic 2 - Answer All Question

Give any one definition of power factor.

What is the value of power if the circuit is (i) purely resistive (ii) Purely inductive or capacitive.

What for an inductor is used? Give some examples.

Draw a graph showing the variation of reactance of (i) a capacitor and (ii) an inductor with the frequency of an a.c circuit.

What is meant by wattles current?

What is meant by power transmission?

State the law that gives the polarity of the induced emf.

What are LC oscillations.

What are step-up and step-down transformers?

How will you define Q-factor?

What is phasort

Define power factor?

Explain the use of transformers in long distance transmission of electric power

What do you mean by resonant frequency?

What are phasors?

What is resonant frequency?

Give the principle of AC generator.

Part - C

Generic 3 - Answer All Question

A solenoid of 500 turns is wound on an iron core of relative permeability 800. The length and radius of the solenoid are 40 cm and 3 cm respectively. Calculate the average emf induced in the solenoid if the current in it changes from 0 to 3 A in 0.4 second.

Distinguish between average & rms value of an AC.

Show that Lenz’s law is in accordance with the law of conservation of energy.

How does the capacitive reactance depend on frequency? & What is the reactance of a capacitor at hertz to the study at?

Explain the working of a single-phase AC generator with necessary diagram.

What do you understand by self-inductance of a coil? Give its physical significance.

How will you induce an emf by changing the area enclosed by the coil?

Give and explain the mechanical analogy of LC oscillations by qualitative treatment.

Find out the phase relationship between voltage and current in a pure inductive circuit.

Establish the fact that the relative motion between the coil and the magnet induces an emf in the coil of a closed circuit.

Part - D

Generic 5 - Answer All Question

Elaborate the standard construction details of AC generator.

Explain mechanical analogy ofLC oscillations by quantitative treatment.

The equation for an alternating current is given by i = 77 sin 314t. Find the peak value, frequency, time period and instantaneous value at t = 2 ms.

A closely wound coil of radius 0.02 m is placed perpendicular to the magnetic field. When the magnetic field is changed from 8000 T to 2000 T in 6 s, an emf of 44 V is induced. Calculate the number of turns in the coil.

Derive an expression for the RMS value of AC.

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Th e fl ux linked with a coil at any instant t is given by \(\Phi\)_B =10t²−50t+ 250 . The induced emf at t = 3s is

An emf of 12V is induced when the current in the coil changes at the rate of 40 A S^-1. The coefficient of self induction of the coil is

What is the value of power if the circuit is
(i) purely resistive
(ii) Purely inductive or capacitive.

Draw a graph showing the variation of reactance of
(i) a capacitor and
(ii) an inductor with the frequency of an a.c circuit.