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physics MCQs

11th • Chapter 10

50 Questions TextBook
1

What is the least distance of distinct vision for a normal human eye?

A
15 cm
B
20 cm
C
25 cm
D
30 cm
2

The magnifying power of an optical instrument is the ratio of the angle subtended by the image to the angle subtended by the object at the __________.

A
unaided eye
B
objective lens
C
eyepiece
D
focal point
3

The resolving power of an instrument is its ability to reveal __________.

A
the color of the object
B
the brightness of the object
C
minor details of the object
D
the speed of the object
4

For light of wavelength λ passing through a lens of diameter D, the resolving power R is given by:

A
D / (1.22 λ)
B
1.22 λ / D
C
λ / (1.22 D)
D
1.22 D / λ
5

The resolving power of a diffraction grating with N rulings in the mth-order is given by:

A
N / m
B
m / N
C
N x m
D
N + m
6

A simple microscope is essentially a __________.

A
concave lens
B
convex lens
C
plane mirror
D
concave mirror
7

For high angular magnification in a simple microscope, the focal length of the convex lens should be __________.

A
large
B
small
C
zero
D
infinite
8

The magnification of a simple microscope is given by the formula M = ?

A
1 + f/d
B
1 - d/f
C
1 + d/f
D
d/f
9

A compound microscope consists of two __________.

A
concave lenses
B
convex lenses
C
plane mirrors
D
a convex and a concave lens
10

In a compound microscope, the objective lens has a __________ focal length compared to the eyepiece.

A
longer
B
very short
C
equal
D
infinitely long
11

The final image formed by a compound microscope in normal adjustment is at the __________.

A
near point (d)
B
far point (infinity)
C
focal point of objective
D
focal point of eyepiece
12

The total magnification M of a compound microscope is the __________ of the magnification of the objective (M1) and the eyepiece (M2).

A
sum
B
difference
C
product
D
ratio
13

What type of image is formed by the objective lens of an astronomical telescope?

A
Virtual, erect, and magnified
B
Real, inverted, and diminished
C
Real, erect, and magnified
D
Virtual, inverted, and diminished
14

In an astronomical telescope in normal adjustment, the distance between the objective and eyepiece is __________.

A
fo - fe
B
fo + fe
C
fo x fe
D
fo / fe
15

The magnifying power of an astronomical telescope is given by M = ?

A
fe / fo
B
fo / fe
C
fo + fe
D
fo - fe
16

To see distant stars, a good telescope should have an objective of __________.

A
small focal length and small aperture
B
long focal length and small aperture
C
small focal length and large aperture
D
long focal length and large aperture
17

A spectrometer is used to study __________ from different sources of light.

A
spectra
B
intensity
C
polarization
D
interference
18

Which part of a spectrometer makes parallel rays of light emerge from its convex lens?

A
Telescope
B
Turn table
C
Collimator
D
Prism
19

In Michelson's experiment to determine the speed of light, what shape was the rotating mirror M?

A
Four-sided
B
Six-sided
C
Eight-sided
D
Twelve-sided
20

The formula derived from Michelson's experiment for the speed of light 'c' is:

A
c = 8fd
B
c = 16fd
C
c = 4fd
D
c = 2fd
21

The accepted value for the speed of light in a vacuum is approximately __________.

A
3.00 x 10^6 m/s
B
3.00 x 10^7 m/s
C
3.00 x 10^8 m/s
D
3.00 x 10^9 m/s
22

The principle behind light propagation in most optical fibres is __________.

A
diffraction
B
dispersion
C
total internal reflection
D
polarization
23

The refractive index 'n' is the ratio of the speed of light in vacuum 'c' to its speed in the material 'v'. What is the formula?

A
n = v / c
B
n = c / v
C
n = c x v
D
n = c - v
24

The critical angle (θc) is the angle of incidence in a denser medium for which the angle of refraction in a rarer medium is __________.

A
0°
B
45°
C
90°
D
180°
25

For a glass-air boundary with glass having n=1.5 and air n=1.0, the critical angle is approximately __________.

A
30.0°
B
41.8°
C
60.0°
D
90.0°
26

The outer layer of an optical fibre with a lower refractive index is called __________.

A
core
B
jacket
C
cladding
D
shield
27

Which type of optical fibre uses a core with a gradually decreasing refractive index from the center to the periphery?

A
Single-mode step-index
B
Multi-mode step-index
C
Multi-mode graded-index
D
Armored fibre
28

Which type of fibre has the thinnest core, around 5 µm, and requires a laser source?

A
Multi-mode graded-index
B
Multi-mode step-index
C
Single-mode step-index
D
Plastic optical fibre
29

In a fibre optic communication system, what component converts electrical signals to light signals?

A
Receiver
B
Photodiode
C
Repeater
D
Transmitter
30

The typical wavelength of the invisible infra-red signals used in fibre optics is __________.

A
0.5 µm
B
1.3 µm
C
5.0 µm
D
10.6 µm
31

What is the most common method of modulation used in fibre optics?

A
Amplitude modulation
B
Frequency modulation
C
Phase modulation
D
Digital modulation
32

In digital modulation, a pulse of light represents the number __________.

A
1
B
0
C
10
D
-1
33

Devices used to regenerate dim light signals in a long-distance fibre optic cable are called __________.

A
amplifiers
B
transmitters
C
receivers
D
repeaters
34

What component at the end of a fibre optic cable converts light signals back to electrical signals?

A
LED
B
Laser
C
Photodiode
D
Collimator
35

The image formed by a convex lens when the object is placed beyond its focus is __________.

A
real and inverted
B
virtual and erect
C
real and erect
D
virtual and inverted
36

For a grating spectrometer, a high resolving power allows it to distinguish small differences in __________.

A
intensity
B
wavelength
C
amplitude
D
speed
37

In a compound microscope, the eyepiece acts as a __________.

A
simple microscope
B
telescope objective
C
collimator
D
diffraction grating
38

The limit to which a microscope can resolve details depends on the width of the __________.

A
eyepiece
B
objective
C
tube
D
observer's eye
39

To produce less diffraction and see more detail, a microscope should use light of __________ wavelength.

A
long
B
medium
C
short
D
any
40

A reflecting telescope uses a large __________ as its objective.

A
convex lens
B
concave lens
C
mirror
D
prism
41

The speed of light in media other than vacuum is always __________ the speed of light in vacuum.

A
greater than
B
equal to
C
less than
D
double
42

An optical fibre with a core diameter of 50 µm and constant refractive index is typically a __________.

A
single-mode step-index fibre
B
multi-mode step-index fibre
C
multi-mode graded-index fibre
D
single-mode graded-index fibre
43

Dispersion in a step-index fibre causes different wavelengths to arrive at __________.

A
the same time
B
different times
C
the same location
D
different angles
44

Which type of fibre is designed to reduce dispersion so that all wavelengths arrive at the other end at the same time?

A
Step-index fibre
B
Single-mode fibre
C
Graded-index fibre
D
Uncladded fibre
45

The time difference for signal arrival in a graded-index fibre is about __________ per km.

A
1 ns
B
33 ns
C
100 ns
D
5 ms
46

What is the final image in an astronomical telescope in normal adjustment?

A
Formed at the near point
B
Formed at infinity
C
Real and inverted
D
Real and erect
47

The refractive index of the core in an optical fibre is __________ than the cladding.

A
lower
B
higher
C
the same
D
negative
48

When angles are small, the angular magnification of a simple microscope can be approximated as __________.

A
q/p
B
I/O
C
d/p
D
p/d
49

The magnifying power of a telescope for viewing distant objects depends on the focal lengths of the __________.

A
objective and the observer's eye
B
objective and eyepiece
C
eyepiece and the observer's eye
D
objective and the object
50

In the formula M = (q/p)(1 + d/fe), the term (1 + d/fe) represents the magnification of the __________.

A
objective
B
final image
C
eyepiece
D
object