(English Medium) ICSE Class 10 - CISCE Question Bank Solutions for Physics

How does the speed of light change when it passes from glass to water? 

A ray of light is passing from a transparent medium 1 to another transparent medium 2 (i) Speed up (ii) slows down. In each case, state whether the refractive index of medium 2 is equal to, less than or greater than the refractive index of medium 1. 

What do you understand by the statement the refractive index of glass is 1.5 for white light? 

The diagram alongside shows the refraction of a ray of light from air to a liquid.

1. Write the values of (i) angle of incidence, (ii) angle of refraction.
2. Use Snell’s law to find the refractive index of liquid with respect to air.

In fig 4.18, name the ray which represents the correct path of light while emerging out through a glass block. 

Fill in the blanks to complete the following sentence 

When light travels from a denser to a rarer medium, its speed ………………. 

Fill in the blanks to complete the following sentence 

The refractive index of glass with respect to air is 3/2. The refractive index of air with respect to glass will be ………………. 

How is the angle of emergence related to the angle of incidence when prism is in the position of minimum deviation? Illustrate your answer with help of a labelled diagram using an equilateral prism? 

Name the colour of white light which is deviated the most on passing through a prism. 

An object is viewed through a glass prism with its vertex pointing upwards. It appears to be displaced upward. Explain the reason. 

Fig 4.31 below shows a light ray of single colour incident normally on two prisms A and B. In each case draw the path of the ray of light as it enters and emerges out of the prism. Mark the angle wherever necessary. 

Complete Fig. 4.32 to show the path of the ray of single colour as it enters the prism and emerges out of it. Mark the angles wherever necessary. 

A pond appears to be 2.7 m deep. If the refractive index of water is `4/3`, find the actual depth of the pond. 

A coin is places at the bottom of a beaker containing water (refractive index = 4/3) to a depth of 12 cm. By what height the coin appears to be raised when seen from vertically above? 

A postage stamp kept below a rectangular glass block of refractive index 1.5 when viewed from vertically above it, appears to be raised by 7.0 mm. Calculate the thickness of the glass slab.

What is meant by the statement the critical angle for diamond is 24°?

The critical angle for glass-air is 45° for the light of yellow colour. State whether it will be less than, equal to, or more than 45° for (i) ref light, (ii) blue light? 

The refractive index of air with respect to glass is expressed as `""_g μ_a=sin i /sin r`.

1. Write down a similar expression for _aμ_g in terms of the angles i and r.
2. If angle r = 90°, what is the corresponding angle i called?
3. What is the physical significance of the angle i in part (b)? 

The refractive index of glass is 1.5. From a point P inside a glass block, draw rays PA, PB and PC incident on the glass air surface at an angle of incidence 30°, 42° and 60° respectively.

1. In the diagram show the approximate direction of these rays as they emerge out of the block.
2. What is the angle of refraction for the ray PB? 

`("Take" sin 42° =2/3)` 

A ray of light enters a glass slab ABDC as shown in figure and strikes at the centre O of the circular part AC of the slab. The critical angle of glass is 42°. Complete the path of the ray till it emerges out from the slab. Mark the angles in the diagram wherever necessary.