Geometric optics Quiz 1

Question 1

Fill in the blanks: In the visible spectrum, the lower end is always marked by _. This is because the wavelength of _ is greater than that of _. Consequently, the refractive index of _ is greater than _. As deviation is given by $$\delta =(\mu -1)A$$, deviation of _ is greater than that of _. Hence, _ colour is always at the upper end of the visible spectrum.

Accepted Answer

violet; red; violet; violet; red; violet; red; red

Answer

red; violet; red; red; violet; red; violet; violet

Answer

violet; red; violet; violet; red; red; violet; red

Answer

red; red; violet; violet; red; violet; red; violet

Question 2

Mary joined four lenses in such a way that they form a system as a whole. If the individual powers of these four lenses are $$+5	ext{D, +9D, }-13	ext{D and }-	ext{7D}$$ respectively then what can be said about the system of lenses?

Accepted Answer

The system behaves as concave

Answer

The system behaves as convex

Answer

The system behaves as both convex and concave

Answer

Cannot be predicted

Question 3

Daniel is experimenting with two lenses by bringing them closer to each other. One lens has a power of $$+4	ext{ }D$$ whereas the other has a focal length of $$f$$. Determine $$f$$ at $$t=6	ext{ s}$$, when both the lenses are $$	ext{12}	ext{.5 cm}$$ apart and has a combined power of $$+7	ext{ }D$$.

Accepted Answer

$$0.16	ext{ m}$$

Answer

$$0.07	ext{ m}$$

Answer

$$0.07	ext{ cm}$$

Answer

$$	ext{0}	ext{.16 cm}$$

Question 4

Ashish and his younger brother were playing with a glass prism. Ashish, who is a student of physics was curious to know the specifications of the prism and started searching for its box. After finding the information provided in its box, he could understand that the prism was made up of glass and had a refractive index of $$1.532$$. He could also understand that the angle of the prism is $$60{}^\circ $$.His younger brother was rotating the prism in a uniform manner when Ashish had an idea to torch light on one of the prism’s open faces. He could observe refraction of torch light through this prism and eagerly showed it to his brother. On the same day at night, Ashish measured the minimum angle of deviation of this prism as:

Accepted Answer

$$40{}^\circ $$

Answer

$$30{}^\circ $$

Answer

$$50{}^\circ $$

Answer

$$20{}^\circ $$

Question 5

Krishna is a physicist and he has many optical instruments with him, out of which some are broken. One fine day, his son, Veer finds one such broken telescope and finds a transparent curved glass piece inside it. He asked his dad what it was and he replied back the answer. What was Krishna’s reply?After having studied about this piece of glass, the next day, Veer coloured its curved surface with silver paint and calculated its new focal length to be $$6	ext{ cm}$$. If its radius of curvature is $$8	ext{ cm}$$ then what was its actual focal length?

Accepted Answer

Plano-convex lens; $$72	ext{ cm}$$

Answer

Plano-convex lens; $$	ext{36 cm}$$

Answer

Plano-concave lens; $$	ext{54 cm}$$

Answer

Plano-concave lens; $$	ext{24 cm}$$