Some Important MCQs related to Light Reflection and Refraction.
Refraction of light
When a ray of light enters from one medium to another, it deviates from its original path, this phenomenon of light is called refraction.
Refraction of light
Refraction is the phenomenon of bending of light, when light rays enter from one medium to another, then it bends from its original path, this phenomenon is called refraction. This is due to the change in the speed of light when it passes from one medium to another.
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| Refraction of light |
Refraction is the phenomenon of bending of light, when light rays enter from one medium to another, then it bends from its original path, this phenomenon is called refraction. This is due to the change in the speed of light when it passes from one medium to another.
Causes of Refraction
Change of speed of light changes the direction of light. The change in speed of light results in a change in the direction of the light ray.
Laws of Refraction
- The incident ray normal and the refracting ray all lie in the same plane.
- The ratio of the sine of the angle of incidence to that of the angle of refraction remains constant. This is called Snell's law.
`\frac{sin i}{sin r} =`constant
`\frac{sin i}{sin r} = \mu`
Where `\mu =` refractive index
Some real-life Experience
(ii)A pencil immersed in water appears to be bent.
(iii)The sun becomes visible 2 minutes before sunrise and up to two minutes after sunset, thus increasing the length of the day by 4 minutes.
(iv) Stars twinkle in the sky.
Phenomenon Related to Refraction of Light
(1)Twinkling of Stars in night
(2)The sun rise and sun set
(3)Appearance of bottom raised of a liquid
(4)Bending of an object
(5)Refraction through a Glass Slab
Reflection of Light
“When light rays strike a shiny surface, they return back to the same medium, this phenomenon of light is called reflection. The speed of light remains constant in the event of reflection.”
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| Reflection of light |
When a ray of light is incident on a smooth polished surface, the light ray returns back to the same medium, it is called reflection of light.
The light ray coming from the light source to the surface is called incident light ray.
The light ray returning after the phenomenon of reflection is called the reflected light ray.
The imaginary line perpendicular to the reflecting surface is called normal,
The surface from which reflection occurs is called reflective surface.
Laws of Reflection
First Law of Reflection- The incident ray, normal, and the reflected ray all lie in the same plane.
Second Law of Reflection - Both the angle of incidence and the angle of reflection are equal.
Angle of incidence = Angle of reflection
`\angle i = \angle r`
Light Reflection and Refraction MCQ
Light- Reflection and Refraction-MCQ 1
Focal length of plane mirror is
(1) At infinity
(2) Zero
(3) Negative
(4) None of these
Ans:
(1) At infinity
Light- Reflection and Refraction-MCQ 2
Image formed by plane mirror is
(1) Real and erect
(2) Real and inverted
(3) Virtual and erect
(4) Virtual and inverted
Ans:
(3) Virtual and erect
Light- Reflection and Refraction-MCQ 3
A concave mirror gives real, inverted and same size image if the object is placed
(1) At F
(2) At infinity
(3) At C
(4) beyond C
Ans:
(3) At C
Light- Reflection and Refraction-MCQ 4
Power of the lens is - 4 m, its focal length is
(1) 4 m
(2) - 40 m
(3) - 0.25 m
(4) - 25 m
Ans:
(3) - 0.25 m
Light- Reflection and Refraction-MCQ 5
A concave mirror gives virtual, refract and enlarged image of the object but image of smaller size than the size of the object is
(1) At infinity
(2) Between F and C
(3) Between P and F
(4) At E
Ans:
(3) Between P and F
Light- Reflection and Refraction-MCQ 6
In optics an object which has higher refractive index is called
(1) Optically rarer
(2) Optically denser
(3) Optical density
(4) Refractive index
Ans:
(2) Optically denser
Light- Reflection and Refraction-MCQ 7
The optical phenomena, twinkling of stars, is due to
(1) Atmospheric reflection
(2) Total reflection
(3) Atmospheric refraction
(4) Total refraction
Ans:
(3) Atmospheric refraction
Light- Reflection and Refraction-MCQ 8
Convex lens focus a real, point sized image at focus, the object is placed
(1) At focus
(2) Between F and 2F
(3) At infinity
(4) At 2F
Ans:
(3) At infinity
Light- Reflection and Refraction-MCQ 9
The unit of power of lens is
(1) Metre
(2) Centimeter
(3) Diopter
(4) `m^\(-1)`
Ans:
(3) Diopter
Light- Reflection and Refraction-MCQ 10
The radius of curvature of a mirror is 20 cm the focal length is
(1) 20 cm
(2) 10 cm
(3) 40 cm
(4) 5 cm
Ans:
(2) 10 cm
Light- Reflection and Refraction-MCQ 11
When a plane mirror is rotated through a certain angle, the reflected ray turns through twice as much and the size of the image:
(1) is doubled
(2) is halved
(3) becomes infinite
(4) remains the same
Ans:
(4) remains the same
Refraction Question 12
If an object is placed symmetrically between two plane mirrors, inclined at an angle of 72 degrees, then the total no. of images formed is:
(1) 5
(2) 4
(3) 2
(4) infinite
Ans:
(2) 4
Refraction Question 13
Which statement is true for the reflection of light?
(1) The angle of incidence and reflection are equal.
(2) The reflected light is less bright than the incident light.
(3) The sum of the angle of incidence and reflection is always greater than 900.
(4) The beams of the incident light, after reflection, diverge at unequal angles.
Ans:
(1) The angle of incidence and reflection are equal.
Refraction Question 14
The focal length of a plane mirror is
(1) 0
(2) infinite
(3) 25 cm
(4) -25 cm
Ans:
(2) infinite
Refraction Question 15
One lite ray is passes through the focus and other other is incident to pole of a concave mirror then-
Where would the reflected rays meet for the image formation to take place?
(1) Behind the mirror
(2) Between F and O
(3) Between C and F
(4) Beyond C
Ans:
(3) Between C and F
Refraction Question 16
A beam of light incident on a plane mirror forms a real image on reflection. The incident beam is:
(1) parallel
(2) convergent
(3) divergent
(4) not certain
Ans:
(2) convergent
Refraction Question 17
An object is placed at a distance of 40cm in front of a concave mirror of a focal length of 20 cm.
(1) virtual and inverted
(2) real and erect
(3) real, inverted and of the opposite size as that of the object
(4) real, inverted and of the same size as that of the object
Ans:
(4) real, inverted and of the same size as that of the object
Refraction Question 18
A student conducts an experiment using a convex lens. He places the object at a distance of 60 cm in front of the lens and observes that the image is formed at a distance of 30 cm behind the lens. What is the power of the lens?
(1) 0.005 Diopter
(2) 0.05 Diopter
(3) 5 Diopter
(4) 50 Diopter
Ans:
(3) 5 Diopter
Refraction Question 19
An image of an object produced on a screen which is about 36 cm using a convex lens. The image produced is about 3 times the size of the object. What is the size of the object?
(1) 12 cm
(2) 33 cm
(3) 39 cm
(4) 108 cm
Ans:
(1) 12 cm
Refraction Question 20
The image formed by a convex spherical mirror is:
(1) Virtual
(2) real
(3) enlarged
(4) inverted
Ans:
(1) Virtual
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