Ray Optics and Optical Instruments quiz

The relation between focal length and radius of curvature of a spherical mirror is:

An optical fibre works on the principle of:

The SI unit of power of a lens is:

Two lenses of power +3 D and -1 D in contact have a combined power of:

Total internal reflection can occur when light travels from:

A convex mirror always forms an image that is:

The magnifying power of a simple microscope with final image at the near point D is:

The magnifying power of an astronomical telescope in normal adjustment is:

The thin lens formula is:

A diamond sparkles mainly because of its:

Why does a pencil partly immersed in water appear bent? (2 marks)

Why are convex mirrors used as rear-view mirrors in vehicles? (2 marks)

How does the focal length of a convex lens change when it is immersed in water? (2 marks)

Explain the formation of a mirage in deserts. (2 marks)

Why should the objective of a telescope have a large aperture? (2 marks)

Why is the objective of a compound microscope of short focal length? (2 marks)

Define the principal focus of a concave mirror. (2 marks)

Write the relation between refractive index and critical angle. (2 marks)

Why does a ray passing through the optical centre of a thin lens go undeviated? (2 marks)

State two advantages of a reflecting telescope. (2 marks)

An object is placed 30 cm in front of a convex mirror of focal length 20 cm. Find the position and magnification of the image. (3 marks)

Find the speed of light in glass (n = 1.5) and in water (n = 4/3), given c = 3 x 10^8 m/s. (3 marks)

Find the power of a concave lens of focal length 25 cm. What is the power of its combination with a +2 D lens in contact? (3 marks)

A prism has an angle of 60 degrees and a refractive index of sqrt(2). Find the angle of minimum deviation. (3 marks)

Find the magnifying power of a simple microscope of focal length 5 cm when the image is formed (i) at the near point (25 cm) and (ii) at infinity. (3 marks)

Read the passage and answer the questions. Optical fibres used for internet connections have a glass core of refractive index 1.68 surrounded by cladding of refractive index 1.44. Light entering the core is trapped and carried for long distances. (i) Find the critical angle at the core-cladding boundary. (ii) Why must the cladding have a lower refractive index? (iii) State one medical use of optical fibres. (5 marks)

Read the passage and answer the questions. On a hot summer day, a driver on a highway sees what looks like a pool of water on the road ahead, which disappears as he approaches. (i) Name the phenomenon. (ii) Explain how the air layers cause it. (iii) Is the image real or virtual? (5 marks)

Read the passage and answer the questions. Vehicles use convex mirrors as side-view mirrors, labelled Objects in mirror are closer than they appear. (i) Why are convex mirrors used? (ii) Why does the warning appear? (iii) Find the image position of a car 10 m behind a convex mirror of focal length 1 m. (5 marks)

Read the passage and answer the questions. A diamond (refractive index 2.42) is cut with many facets so that light entering it undergoes repeated total internal reflections before emerging. (i) Find the critical angle for diamond (sin 24.4 degrees = 0.413). (ii) Why does a small critical angle help it sparkle? (iii) Compare it with glass of refractive index 1.5. (5 marks)

Read the passage and answer the questions. A student cannot see distant objects clearly beyond 80 cm, though he reads books easily. An optometrist prescribes spectacles. (i) Name the defect. (ii) Which type of lens is required? (iii) Find the focal length and power of the lens. (5 marks)

Derive the mirror formula for a concave mirror forming a real image, with a ray diagram. (6 marks)

Derive the relation for refraction at a convex spherical surface and hence derive the lens maker's formula. (6 marks)

Derive the relation n = sin((A + Dm)/2)/sin(A/2) for a prism and draw the graph of angle of deviation against angle of incidence. (6 marks)

Draw a labelled ray diagram of a compound microscope and derive the expression for its magnifying power. (6 marks)

Draw ray diagrams of an astronomical refracting telescope in normal adjustment and of a Cassegrain reflecting telescope. Derive the magnifying power of the refracting telescope. (6 marks)