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physics MCQs

10th • Chapter 06

50 Questions TextBook
1

Who discovered that when a current passes through a conductor, it produces a magnetic field around it?

A
Michael Faraday
B
Joseph Henry
C
Ampere
D
Lenz
2

The direction of the magnetic field around a straight conductor can be determined by the:

A
Fleming's Left Hand Rule
B
Right Hand Grip Rule
C
Lenz's Law
D
Faraday's Law
3

A coil of wire consisting of many loops is called a:

A
Resistor
B
Capacitor
C
Solenoid
D
Diode
4

The type of temporary magnet created when current flows through a coil is called an:

A
Permanent magnet
B
Bar magnet
C
Horseshoe magnet
D
Electromagnet
5

A force is exerted on a current-carrying wire placed in a magnetic field, as discovered by:

A
Michael Faraday
B
Ampere
C
Oersted
D
Henry
6

The force on a current-carrying wire in a magnetic field is zero when the wire is placed ______ to the magnetic field.

A
perpendicular
B
at 45 degrees
C
parallel
D
at 30 degrees
7

Which rule is used to find the direction of force on a current-carrying conductor in a magnetic field?

A
Right Hand Grip Rule
B
Lenz's Law
C
Fleming's Left Hand Rule
D
Ohm's Law
8

The working principle of electric motors is the:

A
Electromagnetic induction
B
Turning effect on a coil in a magnetic field
C
Heating effect of current
D
Chemical effect of current
9

In a D.C. motor, the part that reverses the direction of current in the coil every half-turn is the:

A
Armature
B
Brushes
C
Slip rings
D
Split-ring commutator
10

A D.C. motor is a device that converts:

A
Mechanical energy into electrical energy
B
Electrical energy into kinetic energy
C
Kinetic energy into potential energy
D
Electrical energy into chemical energy
11

The strength of the magnetic field is defined as the number of magnetic lines of force passing through any:

A
Conductor
B
Surface
C
Point
D
Volume
12

The phenomenon of producing an electric current by moving a wire through a magnetic field was discovered by:

A
Ampere
B
Lenz
C
Michael Faraday
D
Oersted
13

An induced e.m.f. is generated in a wire only when the wire _____ magnetic field lines.

A
is parallel to
B
is stationary in
C
cuts
D
is removed from
14

The value of induced e.m.f. in a circuit is directly proportional to the:

A
resistance of the circuit
B
length of the wire
C
rate of change of magnetic lines of force
D
strength of the magnet
15

Lenz's law is a manifestation of the law of conservation of:

A
Mass
B
Charge
C
Momentum
D
Energy
16

In an A.C. generator, the induced current is maximum when the plane of the coil is ______ to the magnetic field.

A
perpendicular
B
parallel
C
at 45 degrees
D
at 60 degrees
17

The part of an A.C. generator that connects the coil to the external circuit is the:

A
Commutator
B
Armature
C
Slip rings
D
Carbon brushes
18

The phenomenon of production of induced current in one coil due to change of current in a neighboring coil is called:

A
Self-induction
B
Electromagnetism
C
Mutual induction
D
Capacitance
19

A transformer works on the principle of:

A
Self-induction
B
Mutual induction
C
Fleming's Left Hand Rule
D
Lenz's Law
20

A device used to increase or decrease AC voltage is called a:

A
Generator
B
Motor
C
Rectifier
D
Transformer
21

A transformer that has more turns in the secondary coil than the primary coil is a:

A
Step-down transformer
B
Step-up transformer
C
Ideal transformer
D
Auto-transformer
22

In an ideal transformer, which quantity is the same for both the primary and secondary coils?

A
Current
B
Voltage
C
Number of turns
D
Power
23

For high voltage transmission, ______ transformers are used at the power station.

A
step-up
B
step-down
C
isolating
D
small
24

A relay is used to:

A
control a large current with a small current
B
store electric charge
C
measure voltage
D
generate DC current
25

Magnetic Resonance Imaging (MRI) uses the magnetic effect of ______ in the body to create images.

A
iron filings
B
ionic currents
C
blood flow
D
calcium deposits
26

According to the Right Hand Grip Rule, the thumb points in the direction of the:

A
Magnetic field
B
Force
C
Current
D
Voltage
27

What happens to the force on a wire in a magnetic field if the current is increased?

A
It decreases
B
It remains the same
C
It increases
D
It becomes zero
28

In a DC motor, the coil assembly is called the:

A
Commutator
B
Shaft
C
Armature
D
Field coil
29

The magnetic field of a current-carrying solenoid is similar to that of a:

A
Horseshoe magnet
B
Disc magnet
C
Bar magnet
D
Single pole
30

An A.C. generator converts:

A
Electrical energy to mechanical energy
B
Mechanical energy to electrical energy
C
Chemical energy to electrical energy
D
Heat energy to electrical energy
31

In the transformer equation Vs/Vp = Ns/Np, what does 'Ns' represent?

A
Number of primary turns
B
Primary voltage
C
Secondary current
D
Number of secondary turns
32

If a transformer steps up the voltage, it must step down the:

A
Power
B
Frequency
C
Current
D
Energy
33

The core of a transformer is usually made of:

A
Copper
B
Aluminum
C
Soft iron
D
Steel
34

Heat dissipated in transmission cables is given by the formula:

A
V*I*t
B
I^2*R*t
C
V^2/R * t
D
P/t
35

To minimize power loss during transmission, the ______ is kept low.

A
voltage
B
resistance
C
current
D
power
36

Walk-through metal detectors at airports work on the principle of:

A
Static electricity
B
Electromagnetic induction
C
Capacitance
D
Photoelectric effect
37

On a bank credit card, user account information is stored on:

A
a microchip
B
a QR code
C
an engraved number
D
a magnetic strip
38

In Fleming's Left Hand Rule, the forefinger points in the direction of the:

A
Current
B
Force
C
Magnetic Field
D
Voltage
39

If the N-pole of a magnet is moved towards a coil, the face of the coil will act as a:

A
S-pole
B
N-pole
C
No pole
D
Either N or S pole
40

The magnetic field produced by a conductor is stronger ______ the conductor.

A
farther away from
B
only at the ends of
C
inside
D
near
41

Which of the following is NOT a factor that increases the force on the armature of a motor?

A
Increasing the number of turns
B
Increasing the current
C
Decreasing the magnetic field
D
Increasing the area of the coil
42

The basic principle behind the production of electricity is:

A
Mutual Induction
B
Electromagnetic Induction
C
Chemical Reaction
D
Static Electricity
43

What is induced when the number of magnetic field lines passing through a coil changes?

A
Resistance
B
An e.m.f.
C
Capacitance
D
A static charge
44

A step-down transformer has a turns ratio of 100:1. If the primary voltage is 170V, what is the secondary voltage?

A
17000 V
B
170 V
C
1.7 V
D
0.17 V
45

In an A.C. generator, when is the induced e.m.f. at its minimum (zero)?

A
When the coil is horizontal
B
When the coil is rotating fastest
C
When the coil is vertical
D
Never
46

The magnetic poles of a current-carrying solenoid can be found using the:

A
Left hand rule
B
Right hand grip rule for a coil
C
Ohm's Law
D
Faraday's Law
47

The magnetic field lines inside a bar magnet are directed from:

A
north pole to south pole
B
south pole to north pole
C
side to side
D
They do not exist inside
48

The presence of a magnetic field can be detected by a:

A
stationary positive charge
B
small mass
C
stationary negative charge
D
magnetic compass
49

A single magnetic pole ______.

A
can be a north pole
B
can be a south pole
C
can be isolated
D
does not exist
50

A transformer needed to convert 240V to 12V is a:

A
Step-up transformer
B
Step-down transformer
C
Ideal transformer
D
Autotransformer