26. A triangular glass prism has ______ triangular bases and _______ rectangular plane lateral surfaces.

27. The angle between the incident ray and normal is called _________ (i1).

28. The ray which comes out of the outer surface of the prism is called ____________.

29. The angle between the plane surfaces any two sides are called the _________ or refracting angle of prism (A).

30. The angle between the incident ray and emergent ray is called _____________ (d).

31. The refractive index of a prism by using the formula, n =

32. The splitting of white light into different colours (VIBGYOR) is called __________.

33. We can consider that white light is a collection of waves with different ____________.

34. Light is an ______________ wave.

35. The refractive index of a medium depends on _____________ of light.

36. Red colour has ________ wavelength and ___________ colour has shortest wavelength.

37. The relation between the speed of wave (u), wavelength (λ) and frequency (f) is, v= ________. (Frequency (f) may be denoted by ‘u’)

38. Speed of the wave increases with increase in __________ of light.

39. The angle between the incoming and outgoing rays can be anything between ____ and about _______ .

40. The beautiful colours of the rainbow are due to ___________ of the sunlight by millions of tiny water droplets.

41. The rays of sunlight enter the drop near its top surface. At this first refraction, the white light is dispersed into its spectrum of colours, _________ being deviated the most and red the least.

42. The atoms or molecules are called ________________.

43. The intensity of scattered light varies with angle of __________.

44. The intensity is maximum at ______ angle of scattering.

45. The reason for blue sky is due to the molecules _______ and ______.

46. _________ found experimentally that the frequency of scattered light by the liquids is greater than the frequency of incident light.

47. Raman introduced the ____________.

48. Raman effect is helpful to determine the shapes of the ___________.

49. The defect in which people cannot see objects situated before near point is called ________________.

50. ___________ is a vision defect indicating that the power of accommodation of the eye usually decreases with ageing.

51. The reciprocal of focal length is called ___________.