Paper for Entry Test Preparation
Physics 2nd year Chapter No. 15
Total marks:- 200 Time
allowed 40 minutes
Note:- Fill
the appropriate answer of the following questions in the answer sheet. Double
filling and erasing is not allowed. Each question carries equal marks and for
each wrong answer minus one is awarded.
1) The current produced by moving a loop of wire
across a magnetic field is called:
a)
Direct current b)
Magnetic current c)
Alternating current d)
Induced current
2) The phenomenon of generation of induced emf is
called:
a)
Electrostatic induction b)
Magnetic induction c)
Electromagnetic induction d) Electric
induction
3) In magnet coil experiment, emf can be produced
by:
a)
Keeping the coil stationary and moving the magnet b) Keeping the magnet stationary and moving the coil
c)
Relative motion of the loop and magnet d)
All of above
4) When there is no relative motion b/w the magnet
and coil, the galvanometer indicates:
a)
No current in the circuit b) An increasing
current c) A decreasing current d) A constant current
5) A coil of constant area is placed in a constant
magnetic field. An induced current is produced in the coil when:
a)
The coil is distorted b) The
coil is rotated c) Neither
(a) nor (b) d) Both (a) and
(b)
6) Referring to above figure, current in coil P
falls from its maximum value to zero:
a)
At the instant the switch is closed b)
At the instant the switch is opened
c)
When switch is kept open d)
When switch is kept closed
7) The unit of induced emf is:
a)
Volt b)
Nm/As c)
Joule coul-1 d)
Both (a) and (c)
8) The product of induced current and the resistance
of the wire through which the current is passing is called:
a)
Electromagnetic induction b) Induced emf c) Induced current d) Self induction
9) When a conductor is moved across a magnetic
field, the redistribution of charge sets up:
a)
Magnetic field b)
Electrostatic field c) Electromagnetic
field d) All of above
10) When the conductor is moved across a magnetic
field:
a)
Emf induced is similar ro the of the battery b)
Emf induced gives rise to induced current
c)
An emf is induced across its ends d)
All of above
11) Motional emf is called motional:
a)
Electromagnetic force and measured in newtons b)
Electromotive force and is measured in volt
c)
Electromotive force and measured in newtons d)
Electromagnetic force and measured in volts
12) The emf produced due to relative motion b/w a
coil and a magnet is called:
a)
Self induce emf b)
Motional emf c)
Aplied emf d) Both
(a) and (c)
13) The minus sign in the Faraday’s law indicates
that the direction of induced:
a)
Current is such that is gfavours the change in flux b) Emf is such that it oppose the
electromagnetic induction
c)
Emf is such that is oppose the change in flux d)
Both (a) and (b)
14) The rate of change of area is expressed in:
a)
m2s-1 b)
ms-2 c)
m2s-2 d)
ms-1
15) The law of electromagnetic induction is related
to:
a)
Coulomb b)
Ampere c)
Faraday d)
Lenz
16) Faraday’s law of electromagnetic induction has
been used in the construction of:
a)
Galvanometer b)
Voltmeter c)
Electric motor d)
Electric generator
17) The direction of induced current is always so as
to oppose the cause which produces it. This is:
a)
Lenz’s law b)
Ampere’s law c)
Faraday’ law d)
Coulomb’s law
18) The Lenz’ law refers to:
a)
Source voltage b)
Induced emf c)
Induced currents d)
Source current
19) The Lenz’s law is a statement of law of
conservation of:
a)
Charge b)
Energy c)
Kinetic energy d)
Magnetic flux
20) When we study mutual induction b/w the coils,
the primary coil circuit also contains:
a)
A rheostat b)
Battery c)
Galvanometer d) Both
(a) and (b)
21) Emf induced in the secondary is proportional to:
a)
Rate of change of current in the secondary b)
Time rate of change of current in the primary
c)
Change of current in the primary d)
Current passing in the primary
22) Mutual inductance M of two coils depends upon:
a)
Number of turns of the coil b)
Area of cross section of coils
c)
Closeness of coil d)
Nature of the core material
23) The phenomenon in which a changing current in a
coil induces an emf is called:
a)
Mutual induction b)
Magnetic induction c) Self
induction d)
Electrostatic induction
24) Self induced emf is proportional to time rate of
change of current in the coil:
a)
Directly b)
Inversely c)
Sometime (a) Sometime (b) d) Non of
all
25) If the current in the coil itself is increased
by rheostat, the emf induced will be:
a)
In the same direction as that of battery b)
Opposite to that of battery
c)
Sometimes (a) and sometimes (b) d)
Non of all
26) Inductors behave like:
a)
Resistors in D.C circuit b)
Capacitors in A.C circuits c) Resistors
in A.C circuits d) Both (a) and (b)
27) A coil of wire is also called:
a)
Conductor b)
Condenser c)
Inductor d)
Insulator
28) Energy stored per unit volume inside a long
solenoid is called:
a)
Energy b)
Energy density c)
Volume charge density d) Work
29) The principle of an electric generator is based
on:
a)
Ampere’s law b)
Faraday’s law c)
Coulomb’s law d)
Hooke’s law
30) Slip rings used in an A.C generator:
a)
To rotate with coil b)
Slide against stationary carbon brushes
c) Are concentric with the axis
of the loop d)
All of these
31) The alternating current induced by an A.C.
generator rotating with frequency cycle/sec reverses its direction:
a)
2f times per second b) f times
per second c) f/2 times per
second d) 4f times per second
32) An iron cylinder with a number of coils wound
over it is called:
a)
Armature b)
Turbine c)
Generator d)
Transformer
33) Split rings act as:
a)
Slip rings b)
Armature c)
Commutator d)
Galvanometer
34) The fluctuations in the output of a D.C
generator are significantly reduced by using:
a)
One coil b)
Two coils c)
Three coils d)
Multiple coils
35) The output of a D.C generator is:
a)
Pulsating D.C b)
Constant D.C c)
Sinusoidal d)
Square wave
36) If the load in the external circuit is greater,
the current supplied by the generator is:
a)
Small b)
Also greater c) Zero d) Very
small
37) A wire carrying the current placed in a magnetic
field experiences a force, this is the basic principle of:
a)
An A.C. generator b) An
electric motor c)
Transformer d)
Armature
38) The windings of an electromagnet (used in motors)
are called:
a)
Field coils b)
Armature coils c)
Primary coils d)
Secondary coils
39) Tick the device which uses the principle of
motor:
a)
Transformer b)
Galvanometer c)
Rheostat d)
Non of all
40) As the motor speeds up, the back emf:
a)
Increases, and current becomes smaller and smaller b) Decreases and current becomes smaller and smaller
c)
Increases and current becomes greater and greater d) Both (b) and (c)
41) The coil from which the power is delivered to
the circuit is called:
a)
Armature coil b)
Secondary coil c) Field
coil d)
Primary coil
42) The coils of transformer are:
a)
Electrically linked b)
Magnetically linked c) Both
(a) and (b) d) Non of
all
43) The coil of a transformer to which power is
delivered is called:
a)
Secondary coil b)
Primary coil c)
Field coil d)
Armature
44) When current I passes through a resistance R,
the power loss due to heating effect is:
a)
Zero b)
Calculated by I2R c)
Calculated by VI d)
Maximum
45) At the generating power station, the voltage is
stepped:
a)
Up and power is transmitted at low current b)
Down and power is transmitted at high current
c)
Down and power is transmitted at low current d)
Both (a) and (c)
46) In a practical transformer, the output is
always:
a)
Equal to input b) Less
than input c) Greater
than input d) Either (a) or
(c)
47) In order to enhance magnetic flux, the coils of
the transformer are wound on:
a)
Soft iron core b)
Hard steel core c)
Copper core d)
Wooden cylinder
48) Hysteresis loss is the:
a)
Energy expended b) Work
done c) Amount of
charge d) Both (a) and (c)
49) It is possible to transmit A.C. power over long
distance without much loss by:
a)
Transformers b)
Commutators c)
Armatures d)
Thermistors
50) Eddy currents are induced currents which are set
up:
a)
A long the flux lines b)
In a direction perpendicular to the flux
c)
Out of the flux area d)
Only around the core
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