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प्रश्न
Suggest one way, in each case, by which we can detect the presence of Infrared radiations.
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उत्तर
These are detected by a thermopile.
संबंधित प्रश्न
The path of a ray of light passing through a glass prism is shown below:

In this diagram, the angle of prism, angle of incidence, angle of emergence and angle of deviation, respectively, have been represented by:
(A) O, Y, Z and N,
(B) P, Y, M and Z,
(C) O, X, M and Z,
(D) P, X, Z and N.
Describe how you could demonstrate that white light is composed of a number of colours.
Draw a diagram to show the refraction of light through a glass prism. On this diagram, mark
(i) incident ray
(ii) emergent ray, and
(iii) angle of deviation.
In an experiment to trace the path of a ray of light through a triangular glass prism, a student would observe that the emergent ray
(a) is parallel to the incident ray.
(b) is along the same direction of incident ray.
(c) gets deviated and bends towards the thinner part of the prism.
(d) gets deviated and bends towards the thicker part (base) of the prism.
A glass prism is able to produce the spectrum when white light passes through it, but a glass slab doesn’t produce any spectrum. Explain why it is so.
Observe the given figure and answer the following questions.

- Which colour light rays bend most?
- Which colour light rays bend least.
- What is the wavelength of violet light rays?
State the correct sequence (1-7) of colours in the spectrum formed by the prisms A and B, shown in the following figure.

Assertion: We can see the rainbow in the sky when the rain starts falling after a spell of bright sunlight.
Reason: The rainbow is formed due to the dispersion of light.
