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"Light" question number distribution across years
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JAMB questions for "Physics :: Light"
Q1
When an object is placed between the principal focus and the optical centre of a convex lens, it could be used as a 
A
compound microscope 
B
simple microscope 
C
projector 
D
reflecting lens 
E

Answer: B

Light
Q2
The instrument used by designers to obtain different colour patterns is called 
A
sextant 
B
kaleidoscope 
C
periscope 
D
episcope 
E

Answer: A

Light
Q3
The production of pure spectrum could easily be achieved using a 
A
triangular prism only  
B
triangular prism with two concave lenses 
C
glass prism with a pin 
D
triangular prism with two convex lenses 
E

Answer: D

Light
Q4

A glass plate 0.9cm thick has a refractive index of 1.50 . How long does it take for a pulse of light to pass through the plate?

A

3.0 X 10-10s

B

3.0 X 10-11s

C

4.5 X 10-10s

D

4.5 X 10-11s

E

Answer: B

Light
Q5
The phenomenon of light bending round an obstacle is 
A
reflection
B
diffraction
C
polarization 
D
refraction 
E

Answer: B

Light
Q6
An object placed 10cm from a concave mirror of focal length 5cm would have its image 
A
at the radius of curvature 
B
at the centre of curvature 
C
at infinity 
D
10cm from the focus 
E

Answer: B

Light
Q7
A person can focus objects when they lie beyond 75cm from his eyes. The focal length of the lens required to reduce his least distance of distinct vision to 25cm is 
A
75.00cm
B
18.75cm
C
25.00cm
D
37.50cm 
E

Answer: B

Light
Q8
Non luminous objects can be seen because they 
A
emit light 
B
are polished 
C
are near 
D
reflect light 
E

Answer: D

Light
Q9
A submarine is observed to rise from a real depth of 80 m to 60 m in water. Calculate the change in apparent depth. [ Refractive index of water = 4/3 ] 
A
45 m
B
60 m
C
80 m
D
15 m
E

Answer: D

Light
Q10
A real image three times the size of an object is formed 24 cm from a converging mirror. What is the focal length of the mirror ? 
A
8 cm
B
16 cm
C
6 cm
D
12 cm
E

Answer: B

Light
Q11
A thin converging lens has a power of 4.0 diopters. Determine its focal length.
A
0.25m
B
0.03 m
C
5.00m 
D
2.50 m 
E

Answer: A

Light
Q12
The sharpness of the boundary of the shadow of an object is determined by the 
A
rays of light passing through the object 
B
intensity of light striking the object 
C
opacity of the object 
D
nature of the object 
E

Answer: B

Light
Q13
The figure below shows a plot of angles of deviation through a glass prism when light is incident at θ degrees on the prism. The incident angle that produces the minimum deviation is
A
250
B
180
C
350
D
200
E

Answer: A

Light
Q14

In photoelectric effect, which of the following graphs correctly represents the graph of stopping potential V0 against frequency f of incident light?

A
B
C
D
E

Answer: A

Light
Q15
Fluorescent tubes produce light by the 
A
excitation of gas molecules 
B
conduction of solar energy
C
refraction of light by a gas molecules 
D
thermal agitation of electrons in the tube 
E

Answer: A

Light
Q16
What type of mirrors are capable of producing parallel beams of light such as those arising from the headlamps of a car? 
A
Parabolic mirrors 
B
Plane mirrors 
C
Cylindrical mirrors 
D
Spherical mirrors 
E

Answer: C

Light
Q17
What happens to the rays in a parallel beam of light ? 
A
They diverge as they travel
B
They intersect 
C
They converge as they travel 
D
They meet at infinity 
E

Answer: D

Light
Q18
A ray of light makes an angle of 35° with a plane mirror. What is the angle of reflection ?
A
35°
B
55°
C
70°
D
65°
E

Answer: B

Light
Q19
A person can focus an object only when it lies within 200 cm from him. Which spectacles should be used to increase his maximum distance of distinct vision to infinity?
A
Convex lens 
B
Binoculars 
C
Concave lens 
D
Plane glasses 
E

Answer: A

Light
Q20
If u is the object distance and v the image distance , which of the following expressions gives the linear magnification produced by a convex lens of focal  length f?
A
u/f -f 
B
u/v + f 
C
v/f +1
D
v/f -1 
E

Answer: D

Light
Q21
Calculate the angle of minimum deviation for a ray which is refracted through an equiangular prism of refractive index 1.4 
A
60°
B
29°
C
99°
D
90°
E

Answer: B

Light
Q22
The refractive index of the medium M in the diagram below is
A
1√3
B
2√3
C
√3
D
2√3
E

Answer: C

Light
Q23
If an object is placed between two parallel plane mirrors with their reflecting surfaces facing each other, how many images of the object will be formed? 
A
four 
B
Two 
C
Eight 
D
Infinite 
E

Answer: D

Light
Q24
By what factor will the size of an object placed 10cm from a convex  lens be increased if the image is seen on a screen placed  25cm from the lens? 
A
2.5 
B
1.5
C
0.4 
D
15.0
E

Answer: A

Light
Q25
At what position will an object be placed in front of a concave mirror in order to obtain an image at infinity ? 
A
At the centre of curvature
B
Between the principle focus and the centre of curvature 
C
At the pole of the mirror 
D
At the principal focus 
E

Answer: D

Light
Q26
A ray incident on a glass prism undergoes minimum deviation when the 
A
refraction angle equals 90°
B
incident angle is equal to the angle of refraction 
C
incident angle is equal to the angle of emergence
D
incident angle equals 90°
E

Answer: C

Light
Q27
Which of the following pairs of light rays shows the widest separation in the spectrum of white light? 
A
Green and Yellow
B
Indigo and violet
C
Orange and red
D
Blue and red
E

Answer: B

Light
Q28
A ray of light is incident on an equilateral triangular glass prism of refractive index 2/3.  Calculate the angle through which the ray is minimally deviated in the prism.
A
37.2°
B
48.6°
C
30.0°
D
42.0°
E

Answer: A

Light
Q29
The operation of an optical fibre is based  on the principle of 
A
polarization of light 
B
refraction of light 
C
interference of light 
D
dispersion of light 
E

Answer: C

Light
Q30
Calculate the refractive index of the material for the glass prism in the diagram below
A
√2
B
3/2
C
√2/2
D
4/3
E

Answer: A

Light
Q31
A coin placed below a rectangular glass block of thickness 9cm and refractive index 1.5 is viewed vertically above the block. The apparent displacement of the coin is 
A
8 cm
B
6 cm
C
5 cm
D
3 cm
E

Answer: D

Light
Q32
A ray of light which strikes a glass slab from air at normal incidence passes through the slab 
A
deviated and undisplaced at a lower speed
B
undeviated and displaced at a faster speed
C
undeviated and undisplaced  at lower speed 
D
deviated and displaced at a lower speed 
E

Answer: D

Light
Q33
The colours seen in soap bubbles are due to 
A
interference
B
dispersion 
C
diffraction
D
refraction 
E

Answer: B

Light
Q34
To produce an enlarged  and erect image with a concave mirror, the object must be positioned 
A
between the principal focus and the centre of curvature 
B
at the principal focus 
C
between the principal focus and the pole 
D
beyond the centre of curvature 
E

Answer: C

Light
Q35
Which of the following eye defects can be corrected using a cylindrical lens? 
A
Astigmatism 
B
presbyopia 
C
chromatic aberration
D
myopia 
E

Answer: B

Light
Q36
A concave mirror of radius of curvature 40cm forms a real image twice as large as the object . The object distance is 
A
30 cm
B
40 cm
C
60 cm 
D
10 cm 
E

Answer: A

Light
Q37
The eye controls the amount of light reaching the retina by adjusting the 
A
retina 
B
optic nerve 
C
cornea 
D
iris 
E

Answer: D

Light
Q38
The driving mirror of a car has a radius of curvature of 1m. A vehicle behind the car is 4m from the mirror. Find the image distance behind the mirror 
A
9/2
B
8/7
C
4/7
D
4/9
E

Answer: C

Light
Q39
A ray of light strikes a plane mirror at an angle of incidence of 35°. If the mirror is rotated through 10° through what angle is the reflected ray rotated? 
A
20°
B
25°
C
45°
D
70°
E

Answer: A

Light
Q40
The terrestrial telescope has one extra lens more than the astronomical telescope . The extra lens is for 
A
magnification of the image 
B
erection of the image
C
improving the sharpness
D
creating an inverted image 
E

Answer: B

Light
Q41
When a piece of rectangular glass block is inserted between two parallel plate capacitor, at constant plate area and distance of separation, the capacitances of the capacitor will. 
A
decrease
B
increase
C
remain constant 
D
decrease, then increase 
E

Answer: B

Light
Q42
If a ray travelling in air is incident on a transparent medium as shown in the diagram, the refractive index of the medium is given as 
A
sin α/sin β
B
sin β/sin α
C
cos α/sin β
D
cos β/sin α
E

Answer: C

Light
Q43
An engineer intends to deviate a light to deviate a light ray from its path by 120° through reflection from a plane mirror. Calculate the angle of incidence 
A
20°
B
30°
C
40°
D
60°
E

Answer: B

Light
Q44
Total internal reflection occurs when light moves from 
A
air to water
B
water to glass
C
 a dense medium to a less dense medium
D
a less dense medium to a dense medium
E

Answer: C

Light
Q45
A boy observes a piece of stone at the bottom of a river 6.0m deep. If he looks from the surface of the river, what is the apparent distance of the stone from him?  ( Refractive index of water = 4/3)
A
4.5 m
B
5.0 m 
C
5.5 m
D
 8.0 m
E

Answer: A

Light
Q46
What optical instrument can best be constructed with converging lenses of focal lengths 50cm and 5 cm? 
A
Compound microscope 
B
Terrestrial telescope 
C
Astronomical telescope 
D
Galileo's telescope 
E

Answer: C

Light
Q47
A projection lantern is used to  give the image of a slide on a screen . If the image is 24 times as large as the slide and the screen is 72.0m from the projecting lens, what is the position of the slide from the lens? 
A
4.0 m
B
3.5 m
C
3.0 m
D
0.3 m
E

Answer: C

Light
Q48
In the diagram below, a beam of white light travels from a rare to a dense medium. What colours of light do the rays a, b and c respectively represent?
A
Blue, Yellow, and Red
B
Green, Red and Blue
C
Red, Green, and Blue
D
Yellow, Blue, and Red
E

Answer: C

Light
Q49
A man stands 4 m in front of a plane mirror. If the mirror is moved 1m towards the man, the distance between him and his new image is
A
3m
B
5 m
C
6 m
D
10 m
E

Answer: C

Light
Q50
The inside portion of part of a hollow metal sphere of diameter 20 m is polished . The portion will therefore form a
A
concave  mirror of focal length 5 cm
B
concave mirror of focal length 10cm
C
convex mirror of focal length 5 cm
D
convex mirror of focal length 20 cm
E

Answer: A

Light
Q51

The velocities of light in air and glass are 3.0 X 108 ms-1 and 2.0 x 108 ms-1 respectively . If the angle of refraction is 30°, the sine of the angle of incidence is

A

0.33

B

0.50

C

0.67

D

0.75

E

Answer: D

Light
Q52
An astronomical telescopes is said to be in normal adjustment when the
A
eye is accomodated
B
focal length of objective lens is longer than that of eye piece
C
final image is at the near point of eye
D
final image is at infinity
E

Answer: D

Light
Q53
The diagram below shows the prism arrangement in a 
A
binocular
B
spectrometer
C
periscope
D
Projector
E

Answer: C

Light
Q54

The correct shape of the graph of uv against (u + v) for an object distance u and image distance v in an experiment to find the focal length of a convex lens is given as

A
B
C
D
E

Answer: A

Light
Q55
An object O lies at a distance m in front of a concave mirror of focal length f. If m < f, then the final image obtained will be
A
virtual and diminished
B
magnified and erect
C
real and inverted
D
diminished and erect
E

Answer: B

Light
Q56
The most suitable type of mirror used for the construction of a searchlight is the
A
concave mirror
B
convex mirror
C
spherical mirror
D
parabolic mirror
E

Answer: A

Light
Q57
An object is placed in front of two plane mirrors inclined at an angle of &#952;°. If the total number of images formed is 7, find the value of &#952;
A
30°
B
45°
C
51°C
D
90°
E

Answer: B

Light
Q58
The displacement d produced in a glass block of thickness t and refractive index n when an object is viewed through it is
A
t -n
B
t (1 + 1/n)
C
t (1 - 1/n)
D
t( 1/n - 1)
E

Answer: C

Light
Q59
A man wears convex lens glasses of focal length 30 cm in order to correct his eye defect . Instead of the optinum 25cm , his least distance of distinct vision is
A
14 cm
B
28 cm
C
75 cm
D
150 cm
E

Answer: A

Light
Q60
The colours seen in thin films of oil on the road and in soap bubbles are due to 
A
reflection 
B
interference
C
diffraction
D
polarization
E

Answer: C

Light