Question 1 :
$ \dfrac{\sin i}{\sin r} &#160;=$constant, the value of constant depends&#160;upon<br/>a) Pair of media <br/>b) Color of incident light<br/>c) Wave length <br/>d) Refracting nature of material<br/>

Question 2 :
A convex lens has $9\ cm$ focal length and a concave lens has $-18\ cm$ focal length. The focal length of the combination in contact will be

Question 4 :
A lens having focal length $f$ and aperture of diameter $d$ forms an image of intensity $I$. Aperture of diameter $\dfrac {d}{2}$ in central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively.

Question 6 :
Playing with a lens one morning, Rita discovers that if she holds the lens 0.120 m away from a wall opposite to a window, she can see a sharp but upside-down picture of the outside world on the wall. That evening, she covers a lighted lamp with a piece of card on which she has pierced a small hole, 0.005 m in diameter. By placing the lens between the illuminated card and the wall, she manages to produce a sharp image of diameter 0.020 m on the wall. What is the distance between the card and the wall?<br><br>

Question 7 :
Why do high rise buildings have a red light on the top of the building?

Question 10 :
A real image occurs when rays converge. A virtual image occurs when rays

Question 11 :
It is first face of a prism which disperses white light. The statement is

Question 12 :
For which of the following colour, the magnifying power of a microscope will be maximum

Question 17 :
A solid transparent sphere has a small opaque dot at its centre. When observed from outside, the apparent position of the dot will be