185. The colour of the light which travels through glass with minimum speed is
(a) red
(b) violet
(c) green
(d) yellow
186. Primary colours are
(a) colours of the rainbow
(b) colours in the spectrum of white light
(c) colours which cannot be produced by mixing other colours
(d) colours found in nature
187. In the visible spectrum which colour has the shortest wavelength?
(a) Red
(b) Blue
(c) Yellow
(d) Violet
188. When white light passes through a glass prism we get a spectrum on the other side of the prism. In the emergent beam the ray which is deviated least is
(a) the violet ray
(b) the red ray
(c) the green ray
(d) the blue ray
189. Which part of the eye photographic camera?
(a) Lens
(b) Iris
(c) Retina
(d) Eyelid
190. The red colour of the setting sun is due to
(a) the least scattered red colour reaching the eye
(b) the dispersion of sun light occurred in air molecule in atmosphere
(c) the diffraction of sunrays in atmospheric layers
(d) interference of all the rays coming from the sun
191. The image of an object formed on the retina of the eye is
(a) virtual and upright
(b) virtual and inverted
(c) real and inverted
(d) real and upright
192. When one enters a dark room after being in bright light one is not able to see anything clearly for a while because
(a) the retina of the eye moves forward
(b) the retina of the eye moves backward
(c) c).the iris is unable to dilate the pupil immediately to be able to see things
(d) the eye has no power of accommodation
193. Astigmatism, a structural defect of the eye, is due to
(a) the eye lens being thin
(b) the eye lens being thick
(c) lack of symmetry in the curvature of the eye preventing rays of light from being brought to a common focus
(d) the pupil being very small
194. Some persons are not able to see distant objects clearly because the image of the object is focused in front of the retina. This defect is known as
(a) short sight
(b) long sight
(c) astigmatism
(d) presbyopia
195. Holography is the technique of
(a) taking photos of various objects
(b) recording and reproducing three dimensional images
(c) tracing out planets and stars in the sky
(d) transmitting light waves
196. The image of an object formed in a plane mirror
(a) is real
(b) is virtual
(c) can be obtained on a screen
(d) is slightly bigger than the object
197. If an object is placed between two parallel plane mirrors, the number of images formed will be
(a) 1
(b) infinite
(c) 0
(d) 4
198. Sound travels fastest in
(a) air
(b) water
(c) iron
(d) vacuum
199. The velocity of sound in air
(a) increases as the square root of the absolute temperature
(b) decreases with temperature
(c) is independent of temperature
(d) None of these
200. In a longitudinal wave, the direction of propagation of the wave is
(a) the same as the direction of the vibrations of the vibrating body
(b) at right angles to the direction of the vibrations of the vibrating body
(c) Both (a) and (b) above
(d) None of the above