Question 3 :
The focal length of a combination of lenses formed with lenses having powers of $+2.50\ D$ and $-3.75\ D$ will be

Question 4 :
The image formed by the given convex mirror when it is inside focal distance is:

Question 5 :
A person sees his virtual image by holding a mirror very close to the face. When he moves the mirror away from his face, the imagebecomes inverted. What type of mirror he is using

Question 7 :
Refraction index of water is 4/3. Calculate speed of light in water.

Question 9 :
A beam of light passes through a sheet of plastic and out into the air. The beam makes&#160;${\theta}_{1}$&#160;angles with the normal as it passes through the plastic and&#160;the angle the beam of light makes with the normal as it passes into the air is&#160;${\theta}_{2}$.&#160;The refractive index for air is $1$&#160;and&#160;The refractive index&#160;for plastic is $2$.<br/>Calculate the value of $\sin{{\theta}_{2}}$, in terms of ${\theta}_{1}$?

Question 10 :
The expression for the magnification of a spherical&#160;mirror in the terms of focal length (f) and the&#160;distance of the object from mirror (u) is

Question 11 :
The diameter of the reflecting surface of spherical mirror is called ..............

Question 12 :
An image of a bright square is obtained on a screen with the aid of a convergent lens. The distance between the square and the lens is $40\ cm$. The area of the image is nine times larger than that of the square. Select the correct statement(s).

Question 13 :
A concave shaving mirror has a radius of curvature of 35.0 cm. It is positioned so that the (upright) image of a mans face is 2.50 times the size of the face. How far is the mirror from the face?

Question 14 :
Three convex lenses are available having focal lengths of $4 cm, 40 cm$ and $4 m$ respectively. Which one could be used as magnifying glass?

Question 15 :
A short linear object of length $b$ lies along the axis of a concave mirror of focal length $f$ at a distance u from the pole of the mirror. The size of the image is approximately equal to :<br>

Question 16 :
The distance between an object and its doubly magnified image by a concave mirror is: [ Assume $f$ = focal length]

Question 17 :
The reflecting surface is given by $y = \dfrac{10L}{\pi} \sin \dfrac{\pi x}{5L}$. The co-ordinates of the point where a horizontal ray becomes vertical after reflection is:

Question 18 :
Two thin lenses of power $+3.5D, -2D$ are placed in contact. Find the power of lens combination.

Question 19 :
In the table below, column I lists various mirrors &#160;and lenses and column II their uses, qualities or properties.<br/><table class="wysiwyg-table"><tbody><tr><td>column &#160;I</td><td>Column II</td></tr><tr><td>I. Plane mirror</td><td>A. Feels thinner in the middle.</td></tr><tr><td>II. Concave mirror</td><td>B. Always forms virtual image.</td></tr><tr><td>III. Convex mirror</td><td>C. Always forms virtual image of smaller size.</td></tr><tr><td>IV. Concave lens&#160;</td><td>D.&#160;Is used by dentists to examine teeth.</td></tr><tr><td>V. Convex lens</td><td>E. Can be used as reading glass.<br/></td></tr></tbody></table>The correct matching is:

Question 20 :
A ray of light going towards the centre of curvature of a convex mirror ............