ICSEClass XPhysicsSpectrum04 Mark2023 Easy

QQuestion

(a) Infrared radiations are used in warfare. Explain with reason, why.

(b) A ray of light is incident at 45° on an equilateral prism in the diagram below.

A ray of light is incident at 45° on an equilateral prism in the diagram below

(1) Name the phenomenon exhibited by the ray of light when it enters and emerges out of the prism.

(2) State the cause of the above phenomenon mentioned by you.

Exam-ready answer 04 Mark

Answer

(a) Infrared radiations are used for signals during warfare because they are invisible and are not absorbed much by the medium.

(b) (1) Dispersion.

(2) The speed of light in glass changes with wavelength. Different colours have different wavelengths and therefore travel at different speeds in glass, causing dispersion.

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