Question 1 :
A double convex lens of glass of refraction index $\mu$ is immersed in a medium of refractive index $\mu_{1}$. If a parallel beam emerges undeviated through the lens, then:<br/>
Question 2 :
The focal length of an equi biconvex lens of R.I.$=$1.5 is equal to
Question 3 :
A prism splits a beam of white light into its constituent colours. This is so because .......... of different colours is different.
Question 4 :
If two $+5D$ lenses are mounted at some distance apart, the equivalent power will always be negative if the distance is
Question 5 :
A red colour in air has wavelength 760 nm when light passes through water of refractive index $\left( n=\frac { 4 }{ 3 } \right) $, wavelength becomes 570 nm.(wavelength of yellow colour in air is 570 nm).Then colour of red light in water is
Question 6 :
Two plano convex lenses of same material and of focal lengths 20 cm & 5 cm should be arranged such that the combination is free from chromatic aberration. Then effective focal length of the combination will be:
Question 7 :
Suppose you have focused on a screen the image of candle flame placed at the farthest end of the laboratory table using a convex lens. If your teacher suggests you to focus the parallel rays of the sun, reaching your laboratory table, on the same screen, what you are expected to do is to move the:
Question 8 :
A simple microscope consists of a concave lens of power 10D and a convex lens of power 15 D. Its magnification at near point is (least distance of distinct vision, D $=$ 25 cm)<br/>
Question 9 :
A lens acts as a converging lens in air and diverging lens in water. The refractive index of the lens is <br>
Question 10 :
Refraction takes placed at a concave spherical boundary separating glass-air medium. For the image to be real, the object distance $(\mu_{g} = 3/2)$.
Question 11 :
When an object is placed on the principal axis of a convex lens at two different positions, it produces the images with magnification +2 and -4 respectively. How many times more away from the lens the image will be formed in the second position as compared to the first position?<br>
Question 12 :
Light from a point source in air falls on a spherical glass surface whose radius of curvature and refractive index are 20 cm and 1.5 respectively. If the distance of light source from the glass surface is 100 cm, then at which position image will be formed ?
Question 13 :
The plano-convex lens of focal length $20$cm and $30$cm are placed together to form a double convex lens, the final focal length will be :
Question 14 :
Assertion: If objective and eye lenses of a microscope are interchanged then it can work as telescope.
Reason: The objective of telescope has small focal length.
Question 15 :
The radius of curvature of a plano-convex lens  is 20 cm If the refractive index of the material of the lens be 1.5 it will
Question 16 :
The refractive indies of glass and water w.r.t air are $3/2$ and $4/3$ respectively. The refractive index of glass w.r.t water will be
Question 17 :
The power of lens is +2 Dioptre. What is the focal length of this mirror?
Question 18 :
Assertion: By roughening the surface of a glass sheet its transparency can be reduced.
Reason: Glass sheet with rough surface absorbs more light.
Question 19 :
A ray of light passes through an equilateral prism such that the angle of incidence is equal to the angle of emergence and each of these equal to $3/4$ of the angle of the prism. The angle of deviation is<br>
Question 20 :
Assertion: Power of the lens is larger if its focal length is smaller.
Reason: Power of the lens measures the ability to converge or diverge the refracted rays.
Question 21 :
Assertion: The formula connecting u, v and f for a spherical mirror is valid only for mirrors whose sizes are very small compared to their radii of curvature.
Reason: Laws of reflection are strictly valid for plane surfaces, but not for large spherical surfaces.
Question 22 :
A plano-convex lens fits exactly into a plano-concave lens. Their plane surfaces are parallel to each other. If the lenses are made of different material of refractive indices $\mu_{1}$ and $\mu_{2}$ and $R$ is the radius of curvature of the curvature of the curved surface of the lenses, then focal length of the combination is
Question 23 :
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 24 :
A thin convex lens made from crown glass $\displaystyle \left ( \mu = \dfrac{3}{2} \right )$ has focal length f. When it is measured in two different liquids having refractive indices $\dfrac{4}{3}$ and $\dfrac{5}{3} $, it has the focal lengths $f_1$ and $f_2$ respectively. The correct relation between the focal lengths is:
Question 25 :
Assertion: Although the surface of goggles' lens is curved, it does not have any optical power.
Reason:  In case of goggles, both the curved surfaces have equal radii of curvature and have centre of curvature on the same side.
Question 26 :
A concave lens of glass , refractive index 1.5, has both surfaces of same radius of curvature R.On immersion in a medium of refractive index 1.75, it will behave as a :-
Question 27 :
Consider a light source placed at a distance of $1.5m$ along the axis facing the convex side of a spherical mirror of radius of curvature $1m$. The position ($s'$), nature and magnification ($m$) of the image are
Question 28 :
Light travels in two media A and B with speeds $1.8 \times { 10 }^{ 8 } m { s }^{ -1 }$ and $ 2.4 \times { 10 }^{ 8 } m { s }^{ -1 } $ respectively. Then the critical angle between them is
Question 29 :
A biconvex lens of focal length 15 cm is in front of a plane mirror. The distance between the lens and the mirror is 10 cm. A small object is kept at a distance of 30 cm from the lens. The final image is :<br/>
Question 30 :
An object and a screen are mounted on an optical bench and a converging lens is placed between them so that a sharp image is received on the screen. The linear magnification of the image is $2.5$. The lens is now moved $30\ cm$ nearer the screen and a sharp image is again formed on the screen. The focal length of the lens is:
