Question

a) A soap film appears invisible when it approaches a zero-thickness.
In 50 words and/or a figure, explain why.
b) The north pole attracts the south pole of a compass needle allowing navigation. T/F
c) There are 3 colour sensors in the eye with maximum responsivity centered on the
primary colours red, yellow and blue. T/F
d) A “red/green colour blind” person is able to detect only red or green light, not the
other. T/F
e) Unpolarized white light is incident on a glass plate at Brewster’s angle. Some of the
light is reflected, some is transmitted. Describe the polarization and colour of the reflected beam
using 50 words and/or a figure.
f) Describe the polarization and colour of the transmitted beam using 50 words and/or a
figure.

Answer 1

a) As we consider a soap film of thickness of "t".As the light incident on it,some of the light is reflected and some transmitted.These reflected and transmitted are get interferred to each other to form the coloured fringes.when there is zero thickness to the soap film no transmitted light will be observed.So, the soap film is invisible.

b) TRUE,because when the compass placed in a free atmosphere the north pole of earth attacts the south pole of the compass and south pole the earth attarcts the north pole of compass.

c) FALSE,because if we considered the painting RED,BLUE and YELLOW are primary colours

But in physics,RED,GREEN and BLUE are primary colours

d) FALSE,When a person with red/green colour blindness can't able to detect red or green and other colours formed by mixing the red and green