Question 1 :
A vertical ray of light strikes the horizontal surfaceof water.What is the angle of refraction?

Question 2 :
A ray of light travelling inside a rectangular glass block of refractive index $\sqrt2$ is incident on the glass-air surface at an angle o incidence of $45^o$.The refractive index of air is one. Under these conditions the ray will

Question 3 :
A ray of light travelling in air is incident on the plane of a transparent medium. The angle of incident is 45$^o$ and that of refraction is 30$^o$. Find the index of the medium.

Question 4 :
The focal length of a convex lens is $25cm$. Its power will be:

Question 5 :
The image of an object placed in front of a concave&#160;mirror of focal length 12 cm is formed at a point&#160;which is 10 cm more distant from the mirror than the object. The magnification of the image is:<br/>

Question 7 :
The relation between $u, v$ ( u is the object distance and v is the image distance )&#160; and f for mirror is given by:<br/>

Question 8 :
Convex lenses are used in peepholes of house doors for security to provide a view of people or objects outside the doors. Is this statement true or false?<br/>

Question 9 :
Gita arranges some mirrors in group- $1$ and group- $2$ according to the magnification, type of image and size of image from the following data.<table class="wysiwyg-table"><tbody><tr><td>Sr. No.</td><td>Group-$1$</td><td>Group-$2$</td></tr><tr><td>$(1)$</td><td>$&lt;1$ and negative</td><td>Real, inverted and small</td></tr><tr><td>$(2)$</td><td>$&gt;1$ and positive</td><td>Real, inverted and enlarged</td></tr><tr><td>$(3)$</td><td>$&gt;1$ and negative</td><td>Virtual, erect and enlarged</td></tr><tr><td>$(4)$</td><td>$&lt;1$ and positive</td><td>Virtual, erect and small</td></tr></tbody></table>For which of the pairs from the group $1$ and $2$ you disagree.

Question 10 :
When light passes from one medium to another, the physical quantity that remains unchanged is