Q.1: What is a prism?
A piece of transparent medium bounded by three rectangular surfaces and two triangular surfaces.
Q.2: Define the deviation.
Ans. Full bending of a beam of light when crossing in optical medium.
Q.3: Define the deviation angle (D).
Ans. The angle between the incident ray and the emerging ray.
Q.4: What is the relationship between the angle of incidence and the angle of deviation?
Ans. When the angle of incidence begins to increase from a lower value, at the beginning the angle of deviation decreases to a certain limit (angle of minimum deviation) and then increases.
Q.5: How does the deviation angle vary with the wavelength?
Ans. The lower the wavelength, the greater the deviation angle.
Q.6: What is the relationship between wavelength and energy?
Ans. Reverse ratio, ie shorter wavelength, higher is the energy of a colour.
Q.7: What is the prism angle in this experiment?
Resp. 60o.
Q.8: How does the prism angle relate to the angle of deviation?
Answer. The higher the prism angle, the greater the angle of deviation.
Q.9: Give some examples of total internal reflection.
Ans. (A) Mirage (b) Gemstone Shine © Brilliant appearance of the pool water surface as seen from inside the water.
Q.10: When the light enters the prism, is there any change in wavelength frequency?
A. The wavelength decreases but the frequency does not change.
Q.11: What is the relationship between the speed of light © the frequency (υ) and the wavelength (λ)?
Ans. C = υ x λ
Q.12: What is the unit of refractive index?
Ans. There are no units, because it is the relation between two similar quantities.
Q.13: Which of the colours have a maximum and minimum deviation angle?
Ans. The deviation is greater in the violet colour and the smaller is red.
Q.14: Why are the warning signs red?
Ans. Since the deviation in red colour is minimal, therefore, they can be viewed from the maximum distance.
Q.15: Define the dispersion of light.
Ans. Separation of colours present in polychromatic light by a prism.
Q.16: Give any example of dispersion.
Answer Rainbow in the sky because of the water droplets.
Q.17: What are fully reflective prisms?
Ans. The prisms in which the angle of the prism are 90o, 45o and 45o.
Q.18: What type of glass is used to make the prism?
Ans. Crown glass or optical glass.
Q.19: Why is PO equal to OM in this experiment?
Ans. Because the image is formed at the same distance back as the object is in front of the reflecting face of the prism.
Q.20: What is meant by critical angle?
Ans. When refraction occurs from a denser medium to a rare medium, that angle of incidence for which the angle of refraction is 90 ° is called the critical angle.
Q.21: What is the prism that fully reflects?
Ans. It is a glass prism that has angles of 45o, 45o, 90o. It deflects the path of light through 90o or 180o without any loss in intensity.
Q.22: Why do gemstones shine like diamonds?
Ans. These gemstones have high refractive indexes and small critical angles that make the incoming light reflect fully a number of times without much loss of intensity and therefore make their faces look bright.