Worksheet: Spectrum | Physics Class 10 ICSE PDF Download

Part A — Multiple Choice Questions 

Q1. In a glass prism, which colour of visible light is deviated the least?

(a) Violet

(b) Blue

(c) Green

(d) Red

Q2. The total angle of deviation produced by a triangular prism depends on which of the following?

(a) Angle of incidence at the first face

(b) Angle of the prism

(c) Refractive index of the prism material

(d) All of the above

Q3. The band of colours obtained when white light passes through a prism is called:

(a) Reflection

(b) Spectrum

(c) Shadow

(d) Mirage

Q4. Which statement about recombination of colours is correct?

(a) A single prism creates colours from nothing

(b) Two properly aligned prisms can recombine the colours to give white light again

(c) Colours cannot be recombined

(d) Red turns into violet after the prism

Q5. Which part of the electromagnetic spectrum has the longest wavelength?

(a) Ultraviolet rays

(b) X-rays

(c) Radio waves

(d) Visible light

Part B — Short Answer Questions 

Q6. What is dispersion? What is a spectrum? Give one example.

Q7. Why does the deviation in a prism depend on the colour of light?

Q8. Write the order of colours you see on a screen when white light passes through a prism. Which colour deviates the most and which the least?

Q9. A ray is made to enter the same prism with a larger angle of incidence than before. What generally happens to the total deviation?

Q10. The speed of electromagnetic waves in air is 3 × 10^8 metres per second. If the wavelength of a visible light is 600 nanometres, find its frequency.

Part C — Long Answer Questions 

Q11. Describe step by step how a glass prism produces the spectrum of white light. Explain why red bends least and violet bends most.

Q12. White light is dispersed by a prism into seven colours. Explain how a second prism can be used to recombine these colours back into white light. What does this show about the nature of white light and prisms?

Q13. Answer the following questions
(a) Arrange these in order of increasing wavelength: Ultraviolet rays, Visible light, Infrared radiations, Radio waves.
(b) State two properties and one use each of Ultraviolet rays and Infrared radiations.
(c) A microwave signal has a frequency of 3 × 10^9 hertz. Find its wavelength in metres. (Use speed of light = 3 × 10^8 metres per second.)