Practice MCQ Questions and answers on Physics-GK

The phenomenon of change in direction of light when it passes from one medium to another is called refraction.

The refractive index of a transparent medium is most for violet light. The reason is that the speed of violet light is least in a transparent medium while the speed of red light is most in transparent medium.

A magnifying glass (called a hand lens in laboratory contexts) is a convex or converging lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle.

The twinkling of stars and variation in size of the Sun are due to atmospheric refraction of light. Besides, refraction is also responsible for the sun to look during sunset and sunrise. It is also responsible for the sun becoming two or three minutes before actual sunrise. The sun appears higher or lower in the sky due to the changing position of the Earth relative to the Sun.

The bending of light (i.e. refraction of light) as it moves from water to air makes the water tank appear to be less shallower than its real depth.

Total internal reflection is responsible for glittering which occurs when the light from a denser media (liquid) tries to enter less dense media (air in bubble). This reflected light when captured by our eyes is seen as glittering.

The increasing order of the refractive index of certain materials is (left to right) Ice, Kerosene, Benzene, Rock Salt.

Red light suffers the least amount of deviation and violet the most. When a white light is made to pass through a prism, formation of a spectrum of seven colors occurs showing white light is a combination of seven separate colors.

The wavelength and frequency of these deviated colours is different, they deviate differently at different angles due to the velocity difference of the prism. The colour red therefore deviates the least since it has maximum wavelength and colour violet deviates the most since it has the least wavelength.

The apparent depth will look less that its real depth due to the refraction of light. First of all, imagine an object at the bottom of the pond, emitting three beams of light: one straight to the centre of your eye, one above your eye, and one below. Now, as light travels faster in air than it does in water, it will accelerate as it breaks the surface, at which point it bends away from the ‘normal’ - the imaginary line perpendicular to the surface. So back to those three beams, the one coming straight at your eye, and as such perfectly vertical, will not bend one way or another as it leaves the water. The other two beams, however, will bend further away from that middle beam, creating a ‘triangle’ with a larger base, if you were to draw a diagram. These new trajectories, if traced backwards, and ignoring a reverse bending in water, will all meet at a new point, higher than the actual point of origin.