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physics MCQs

12th • Chapter 03

50 Questions TextBook
1

A magnetic field is set up in the region surrounding a?

A
Stationary charge
B
Current carrying wire
C
A piece of cardboard
D
A vacuum
2

According to the right-hand rule, if the thumb points in the direction of the current, what do the fingers indicate?

A
Direction of the force
B
Direction of the electric field
C
Direction of the magnetic field
D
Direction of electron flow
3

The force on a current-carrying conductor in a magnetic field is maximum when the angle between the conductor and the field is?

A
0°
B
45°
C
90°
D
180°
4

The formula for the force on a current-carrying conductor in a uniform magnetic field is?

A
F = BILcosα
B
F = B/ILsinα
C
F = ILBsinα
D
F = IL/B
5

In the equation F = I(L x B), the vector L is in the direction of?

A
The magnetic field
B
The force
C
Perpendicular to the current
D
The current flow
6

The SI unit of magnetic induction (B) is the?

A
Weber (Wb)
B
Ampere (A)
C
Newton (N)
D
Tesla (T)
7

One tesla (T) is equal to?

A
1 NA⁻¹m⁻¹
B
1 N⁻¹Am
C
1 Wbm²
D
1 NA⁻¹m
8

Magnetic flux (Φ) is a scalar quantity given by the dot product of?

A
F and L
B
B and I
C
B and A
D
L and B
9

The unit of magnetic flux is the?

A
Tesla (T)
B
Weber (Wb)
C
Newton (N)
D
Farad (F)
10

Magnetic flux is maximum when the angle between the magnetic field B and the normal to the area A is?

A
90°
B
45°
C
180°
D
0°
11

The phenomenon where a current-carrying conductor in a magnetic field experiences a force is the basis for?

A
Capacitors
B
Electric motors
C
Transformers
D
Resistors
12

Ampere's circuital law relates the magnetic field along a closed path to the?

A
Total charge enclosed
B
Total flux enclosed
C
Total current enclosed
D
Total resistance of the path
13

The constant μ₀ in Ampere's law is known as the?

A
Permittivity of free space
B
Permeability of free space
C
Electric constant
D
Gravitational constant
14

The magnetic field inside a long, tightly wound solenoid is?

A
Weak and non-uniform
B
Strong and non-uniform
C
Uniform and strong
D
Zero
15

The formula for the magnetic field inside a solenoid is?

A
B = μ₀n/I
B
B = μ₀I/n
C
B = μ₀nI
D
B = nI/μ₀
16

The force experienced by a single charge q moving with velocity v in a magnetic field B is given by?

A
F = q(E x B)
B
F = q(v . B)
C
F = q(v x B)
D
F = qvB
17

A charged particle moving parallel to a magnetic field experiences a force of what magnitude?

A
Maximum
B
qvB
C
Minimum
D
Zero
18

The force that is the vector sum of the electric force and the magnetic force on a moving charge is called the?

A
Centripetal Force
B
Gravitational Force
C
Nuclear Force
D
Lorentz Force
19

In the determination of the e/m of an electron, the magnetic force provides the necessary?

A
Kinetic energy
B
Potential energy
C
Centripetal force
D
Linear momentum
20

The path of an electron moving perpendicular to a uniform magnetic field is a?

A
Straight line
B
Parabola
C
Circle
D
Ellipse
21

In a velocity selector, a charged particle moves undeviated when?

A
Magnetic force equals its weight
B
Electric force equals magnetic force
C
Electric force is zero
D
Magnetic force is zero
22

A Cathode Ray Oscilloscope (CRO) is essentially a high-speed?

A
Voltmeter
B
Graph plotting device
C
Ammeter
D
Frequency generator
23

In a CRO, the brightness of the spot on the screen is controlled by the?

A
Anodes
B
Deflection plates
C
Grid
D
Filament
24

The 'time base' or 'sweep' generator in a CRO provides a?

A
Sinusoidal voltage
B
Square wave voltage
C
DC voltage
D
Saw-tooth voltage
25

To display a stable waveform on a CRO, the frequency of the time base generator must be synchronized with the frequency of the?

A
Voltage on the x-plates
B
Voltage on the y-plates
C
Anode voltage
D
Grid voltage
26

The torque on a current-carrying coil in a magnetic field is given by τ = NIABcosα. The torque is maximum when the plane of the coil is?

A
Parallel to the field (α=0°)
B
Perpendicular to the field (α=90°)
C
At 45° to the field
D
Independent of orientation
27

A galvanometer is an instrument used to?

A
Measure large currents
B
Detect the passage of current
C
Measure potential difference
D
Measure resistance
28

In a moving coil galvanometer, a radial magnetic field is used to make the deflecting couple?

A
Proportional to sinα
B
Proportional to cosα
C
Independent of the angle α
D
Zero
29

The sensitivity of a galvanometer can be increased by?

A
Increasing the value of c
B
Decreasing the number of turns N
C
Decreasing the magnetic field B
D
Decreasing the torsional constant c
30

A galvanometer is converted into an ammeter by connecting a?

A
High resistance in series
B
Low resistance in parallel (shunt)
C
High resistance in parallel
D
Low resistance in series
31

A shunt resistor connected to a galvanometer must have a?

A
Very high resistance
B
Resistance equal to the galvanometer
C
Very low resistance
D
Variable resistance
32

An ideal ammeter should have?

A
Infinite resistance
B
Very high resistance
C
A specific non-zero resistance
D
Zero resistance
33

A galvanometer is converted into a voltmeter by connecting a?

A
High resistance in series
B
Low resistance in parallel (shunt)
C
Capacitor in series
D
Inductor in parallel
34

A voltmeter is always connected in ________ with the component across which voltage is to be measured.

A
Series
B
Parallel
C
A combination of series and parallel
D
Any way
35

An ideal voltmeter should have?

A
Zero resistance
B
Very low resistance
C
A specific non-zero resistance
D
Infinite resistance
36

An ohmmeter is a device used for rapid measurement of?

A
Current
B
Voltage
C
Capacitance
D
Resistance
37

In an ohmmeter, when the terminals are short-circuited (R=0), the galvanometer shows?

A
Zero deflection
B
Half-scale deflection
C
Full-scale deflection
D
Infinite reading
38

The 'infinity' mark on an ohmmeter scale corresponds to?

A
Zero current
B
Maximum current
C
A short circuit
D
A known resistance
39

An AVO meter is a multipurpose instrument also known as a?

A
Potentiometer
B
Wheatstone bridge
C
Multimeter
D
CRO
40

A Digital Multimeter (DMM) is preferred over an analogue AVO meter because it?

A
Is heavier
B
Is more complex to use
C
Eliminates human reading error
D
Requires no power
41

The direction of force on a positive charge moving in a magnetic field is given by the?

A
Left-hand rule
B
Right-hand rule for v x B
C
Ampere's law
D
Lenz's law
42

If a wire is grasped in the fist of the right hand with the thumb pointing in the direction of the current, the fingers will circle the wire in the direction of?

A
Force
B
Electric field
C
Magnetic field
D
Voltage
43

The force on a current-carrying conductor is zero if the conductor is placed __________ to the magnetic field.

A
Perpendicular
B
At 45 degrees
C
Parallel
D
At 60 degrees
44

The magnetic flux density is defined as the flux per unit?

A
Volume
B
Length
C
Area perpendicular to the flux
D
Time
45

The magnetic field outside a long solenoid is so weak that it can be?

A
Considered uniform
B
Neglected
C
Used for measurements
D
Stronger than the inside field
46

The function of the soft iron cylinder inside a galvanometer coil is to?

A
Weaken the magnetic field
B
Make the field radial and stronger
C
Provide a path for current
D
Decrease the number of turns
47

A 'dead beat' galvanometer is one in which the coil?

A
Comes to rest quickly
B
Never moves
C
Oscillates indefinitely
D
Is very sensitive
48

What part of a CRO deflects the electron beam horizontally?

A
Y-plates
B
Grid
C
X-plates
D
Anode
49

If two parallel wires carry currents in the same direction, they will?

A
Repel each other
B
Attract each other
C
Have no effect on each other
D
Rotate
50

If an electron (negative charge) moves into a magnetic field, the direction of the force on it is _________ to the direction of force on a proton (positive charge).

A
The same as
B
Perpendicular
C
Opposite
D
At 45 degrees