166. Formation of shadows can be explained by
(a) rectilinear propagation of light
(b) reflection
(c) refraction
(d) total internal reflection
167. When a light ray is reflected repeatedly by a set of parallel plane mirrors, the intensity of light ray diminishes alter a few reflections. This is because of
(a) poor reflection from the mirrors
(b) scattering of light from the mirrors
(c) absorption of some light by the mirrors
(d) absorption of light by the atmosphere
168. The radius of curvature of a spherical mirror is
(a) equal to half its focal length
(b) equal to its focal length
(c) twice its focal length
(d) not related to its focal length
169. A convex mirror always produces
(a) an erect, virtual image of diminished size
(b) an erect, real image of diminished size
(c) an erect, real image of double size
(d) a virtual image of double size
170. To concentrate light on the defective teeth, the dentists use
(a) convex mirrors
(b) concave mirrors
(c) convex lens
(d) concave lens
171. Rays from the headlight of a motor car are rendered parallel by suitably using
(a) a convex mirror behind it
(b) a concave lens behind it
(c) a concave mirror in front of it
(d) a concave mirror behind it
172. A spherical mirror is
(a) a reflecting elliptical portion
(b) a reflecting spherical surface
(c) a parabolic reflecting surface
(d) a flat reflecting surface
173. A series of east moving still pictures can be made to appear as a moving picture because the eye
(a) can focus very rapidly as pictures change
(b) is quicker than the brain
(c) can see two images separated only if the interval’ between seeing them is more than’ one-tenth of a second
(d) can shut out some of the light
174. When an incident beam of light strikes the surface of a glass slab normally, the refracted beam
(a) goes straight through without bending
(b) gets deviated away from the normal
(c) gets bent towards the normal
(d) gets reflected
176. When light travels from one medium to another there is a change in its
(a) velocity
(b) wavelength
(c) frequency
(d) Both (a) and (b) above
177. We see the sun before it actually rises on the horizon. This is due to
(a) refraction
(b) reflection
(c) total internal reflection
(d) parallax
178. The mirage is a phenomenon
(a) generally considered as a desert happening
(b) caused by unequal heating of the several layers of the atmosphere above the desert
(c) in which the refracted rays take a curved path resulting in total internal refection
(d) All the above
179. Diamond shines because of its
(a) purity
(b) hardness
(c) high density
(d) high refractive index and low critical angle
180. For viewing objects placed at a higher level from a position at a lower level, the instrument used’ Is known aa
(a) telescope
(b) spectrometer
(c) microscope
(d) periscope
181. Dioptre is the unit of power of
(a) convex mirrors
(b) concave mirrors
(c) concave lenses
(d) lenses irrespective of types
182. The power of a lens is
(a) equal to its focal length
(b) equal to its radius of curvature
(c) equal to the reciprocal of its focal length (in metres)
(d) equal to twice its focal length
183. The wavelengths of the visible spectrum extend from
(a) 1000 Å to 6000 Å approximately
(b) 4000 Å to 7500 Å
(c) 16000 Å to 25000 Å
(d) 8000 Å to 16000 Å
Note: 1 Å (Angstrom) = 10-10m
184. Arrange the following regions of the spectrum of electromagnetic radiations in the descending order of their frequencies.
I. Infrared waves
II. X-rays
III. Microwaves
IV. Visible spectrum
(a) I, II, Ill, IV
(b) IV, II, I, III
(c) II, IV, I, III
(d) II, Ill, IV, I