(a) A coin kept inside water [μ = 4/3] when viewed from air in a vertical direction appears to be raised by 3.0 mm. Find the depth of the coin in water. (b) How is the critical angle related to the refractive index of a medium?

Small air bubbles rising up a fish tank appear silvery when viewed from some particular angle is due to the: (a) reflection (b) refraction (c) dispersion (d) total internal reflection

Speed of blue light in water is: (a) more than green light (b) more than orange light (c) more than violet light (d) more than red light

When a ray of light travels normal to the given surface, then the angle of refraction is: (a) 180° (b) 90° (c) 0° (d) 45°

(a) Out of the three rays (I, J, H) shown in the diagram, which ray will suffer Total Internal Reflection while inside the prism? (Critical angle of the prism is 42°.) (b) Copy the diagram to complete the path of the ray which you have named in (a) till it comes out of the prism.

A monochromatic ray of light is incident on an equilateral prism placed at minimum deviation position with an angle of incidence 45° as shown in the diagram. (a) Copy the diagram and complete the path of the ray PQ. (b) State two factors on which the angle of deviation depends.

Light travels a distance of ‘10x’ units in time ‘t1’ in vacuum and it travels a distance of ‘x’ units in time ‘t2’ in a denser medium. Using this information answer the question that follows: (a) ‘Light covers a distance of ‘20x’ units in time ‘t1’ in diamond.’ State true or false. (b) Calculate the refractive index of the medium in terms of ‘t1’ and ‘t2’.

(a) Refractive index of glass with respect to water is . Find the refractive index of water with respect to glass. (b) Name the principle used to find the value in part (a). (c) If we change the temperature of water, then will the ratio remain the same? Write yes or no.

A monochromatic ray strikes the surface of identical prisms (A, B and C) at different angles of incidence. The diagram below shows their refracted rays. Study the path of these refracted rays and identify in which of the diagrams: (a) the angle of incidence is maximum. (b) the angle of incidence is minimum. (c) the angle of incidence is equal to the angle of emergence.

A ray of light enters a rectangular glass slab submerged in water at an angle of incidence 55°. Does this ray undergo total internal reflection when it moves from water to glass? Justify your answer. (The critical angle for glass–water interface is 54°)

Two rays PQ and RS are incident on a rectangular glass block as shown in the diagram. Observe the diagram and answer the questions that follow. Which of these two rays will: (a) have greater lateral displacement on emerging out of the block? (b) travel with greater speed in the block? (c) scatter more in the atmosphere?

Complete the following by choosing the correct answers from the bracket: (a) In uniform circular motion the centrifugal force acts ............... [towards the centre/away from the centre/along the tangential direction]. (b) Refractive index of a medium is independent of ............... [temperature/angle of incidence/wavelength of light]. (c) Heat absorbed during change of phase depends on ............... [mass/change in temperature/specific heat capacity] of the substance. (d) Emf of a cell is ............... [greater than/less than/equal to] the terminal voltage when the cell is in open circuit. (e) In a step-up transformer the turns ratio is ............... [more than 1/less than 1/equal to 1]. (f) The nuclear radiation with lowest ionising power is ............... [α/β/γ].