Class 10th Physics Unit 12 Geometrical Optics MCQs Short Long Notes

physics 10th notes ch 12

1. The speed of light is greater in: 

 
 
 
 

2. In a lens, number of curved surfaces will be at least:

 
 
 
 

3. The bending of light as it passes from one transparent medium into another is:

 
 
 
 

4. It is used to explore the interior organs of the body?

 
 
 
 

5. The distance from the pole to the principal focus measured along the principal axis is:

 
 
 
 

6. The relationship between object distance p, image distance q from the mirror and focal length of the mirror is called:

 
 
 
 

7. In totally reflecting prism one angle is of 90°, and other two angles are of:

 
 
 
 

8. Conditions for total internal reflection are: 

 
 
 
 

9. The lens which causes incident parallel rays to converge at a point is:

 
 
 
 

10. ? =   speed of light in vacuum / speed of light in medium

 
 
 
 

11. A line joining centre of curvature and pole of the spherical mirror is:

 
 
 
 

12. Critical angle is equal to:

 
 
 
 

13. The study of behaviour of light is called;

 
 
 
 

14. Endoscope which is used to diagnose throat is;

 
 
 
 

15. sin i / sin r = n = n2/n1

 
 
 
 

16. The speed of light in water is approximately: 

 
 
 
 

17. The angle at which prism deviates the incident ray is called:

 
 
 
 

18. The line passing through the two centres of curvatures of the lens is called: 

 
 
 
 

19. In concave mirror which surface is reflecting?

 
 
 
 

20. In totally reflecting prism one angle is of:

 
 
 
 

21. It is a transparent body (made of optical glass) with at least two polished plane faces inclined towards each other from which light is refracted:

 
 
 
 

22. Lens thick at the centre but thin at the edges is:

 
 
 
 

23. If a ray of light in glass is incident on an air surface at an angle greater than the critical angle, the ray will be: 

 
 
 
 

24. Endoscope used to diagnose the stomach is;

 
 
 
 

25. The minimum value of angle of deviation is called:

 
 
 
 

26. To see from submarine and the ship at the surface of water, we use:

 
 
 
 

27. Optical fibre works on the principal of:

 
 
 
 

28. Which statement is incorrect about concave mirror? 

 
 
 
 

29. Which statement is correct about convex mirror? 

 
 
 
 

30. SI unit of power of lens is:

 
 
 
 

31. Optical fibres are:

 
 
 
 

32. It has positive focal length:

 
 
 
 

33. The refractive index of internal coating of optical fibre is:

 
 
 
 

34. The distance between the optical centre and the principal focus is:

 
 
 
 

35. When a ray of light enters from a denser medium to a rarer medium: 

 
 
 
 

36. 1D = ?

 
 
 
 

37. Lens formula is

 
 
 
 

38. Totally reflecting prism turns the incident ray at an angle of:

 
 
 
 

Short Questions

A man raises his left hand in a plane mirror, the image facing him is raising his right hand. Explain why?
Define convex lens and concave lens.
Define Critical angle.
Define lens.
Define optical centre and focal length of lens?
Define optical fibre.
Define refractive index. 
Define total internal reflection.
Define unit of power of lens
Describe the passage of light through parallel sided transparent material. 
Differentiate between concave and convex mirrors.
Differentiate between core and cladding of an optical fibre.
Differentiate between the focus of a concave &\quad convex mirror?
Draw the ray diagram for the virtual image in a plane mirror?
Explain the reflection of light by spherical mirrors with the help of diagram.
Explain why a fish under water appears to be at a different depth below the surface than it actually is. Does it appear deeper or shallower?
How does the thickness of a lens affect its focal length?
How does the combination of two triangular prisms resemble a concave or convex lens?
How light travels with the use of total internal reflection in optical fibre.
In your own words, explain why light waves are refracted at a boundary between two materials.
State law of refraction?
State Snell’s law?
Under what conditions will a converging lens form a virtual image?
Under what conditions will a converging lens form a real image that is the same size as the object?
What are spherical mirrors? 
What are the characteristics of focus of a concave and a convex mirror?
What are the sign conventions for focal length in lenses?
What are the sign conventions for image distance in lenses?
What are the sign conventions for object distance in lenses?
What do you know about power of lens?
What do you know about principal axis and principal focus of lens?
What is Lens formula?
What is meant by mirror formula? 
What is meant by refraction of light?
What is prism?
What is the relation between focal length and radius of a spherical mirror? 
When an optician’s testing room is small, he uses a mirror to help him test the eyesight of his patients. Explain why.
Why is the driver’s side mirror in many cars convex rather than plane or concave?
Why do we use refracting telescope with large objective lens of large focal length?
Why or why not concave mirrors are suitable for makeup?
Why the focal length of a convex mirror is taken as negative?
Why the term magnification does is different from the term enlargement in optics?
Write conditions of total internal reflection.
Write down the sign conventions for concave and convex mirror.
Write down the uses of lens.

Long Questions

What do you understand by reflection of light? Draw a diagram to illustrate reflection at a plane surface.
A ray of light from air is incident on a liquid surface at an angle of incidence 35 . Calculate the angle of refraction if the refractive index of the liquid is 1.25. Also calculate the critical angle between the liquid air inter-face.
A convex lens of focal length 6 cm is to be used to form a virtual image three times the size of the object. Where must the lens be placed?
An image is produced by a concave mirror of focal length 8.7 cm. The object is 13.2 cm tall and at a distance 19.3 cm from the mirror . (a) Find the location and of the image. (b) Find the height of the image produced by the height mirror if the object is twice as far from the mirror .
An image of a statue appears to be 11.5 cm behind a concave mirror with focal length 13.5 cm. Find the distance from the statue to the mirror .
An object 10 cm high is placed at a distance of 20 cm from a concave lens of focal length 15 cm. Calculate the position and size of the image. Also, state the nature of the image.
An object 10.0 cm in front of a convex mirror forms an image 5.0 cm behind the mirror . What is the focal length of the mirror?
An object 30 cm tall is located 10.5 cm from a concave mirror with focal length 16 cm. (a) Where is the image located? (b) How high is it?
An object 4 cm high is placed at a distance of 12 cm from a convex lens of focal length 8 cm. Calculate the position and size of the image. Also state the nature of the image.
An object and its image in a concave mirror are of the same height, yet inverted, when the object is 20 cm from the mirror . What is the focal length of the mirror?
Define refraction of light. Describe the passage of light through parallel-sided transparent material.
Define the following terms applied to a lens:
(i) principal axis (ii) optical centre (iii) focal length
Define the following terms used in refraction:
(i) angle of incidence (ii) angle of refraction
Describe the following terms used in reflection:
(i) normal (ii) angle of incidence (iii) angle of reflection
Describe how light is refracted through convex lens.
Find the focal length of a mirror that forms an image 5.66 cm behind the mirror of an object placed at 34.4 cm in front of the mirror . Is the mirror concave or convex?
Nabeela uses a concave mirror when applying makeup. The mirror has a radius of curvature of 38 cm. (a) What is the focal length of the mirror? (b) Nabeela is located 50 cm from the mirror . Where will her image appear? (c) Will the image be upright or inverted?
State laws of reflection. Describe how they can be verified graphically.
State the laws of refraction of light and show how they may be verified using rectangular glass slab and pins.
The power of a convex lens is 5 D. At what distance the object should be placed from the lens so that its real and 2 times larger image is formed.
What are optical fibres? Describe how total internal reflection is used in light propagating through optical fibres.
What is meant by the principal focus of a (a) convex lens (b) concave lens?
Illustrate your answer with ray diagrams.
What is critical angle? Derive a relationship between the critical angle and the refractive index of a substance.
What is meant by the term total internal reflection. State the conditions for total internal reflection.
What is meant by refractive index of a material? How would you determine the refractive index of a rectangular glass slab?
With the help of a ray diagram, how you can show the use of thin converging lens as a magnifying glass.

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