A cubical block of glass is placed on a printed page lying on a horizontal surface. Then the minimum value of refractive index of glass for which the letters in the page are not visible from any of the vertical faces of the block is
√2
less than √2
2
between √2 and 2
What will be the wave length of sodium light in glass if it is 589.3nm in the air? The refractive index of glass is 1.5.
589.3x1.5nm
(589.3/1.5)nm
589.3nm
None of the above
A parallel beam is incident on a convex lens of focal length f. It is then put in contact with a concave lens of focal length f/2. What will happen to the image?
Real, at v = f/2
Real, at v=f
virtual, at v = f/2
virtual at v=f
A double convex lens of focal length f is cut into 4 equivalent parts. One cut is perpendicular to the axis and the other is parallel to the axis of the lens. What is the focal length of each part?
f/2
f
2f
4f
The distance of the image from the focus of a lens is x and that of object is y. What is the nature if the graph y versus x?
straight line
ellipse
parabola
Hyperbola
A convex lens of focal length 25cm is placed at a distance x from a concave lens of focal lenght 7cm. When a parallel beam is incident on the convex lens it emerges as a parallel beam out of the concave lens. What is the value of x?
20cm
18cm
16cm
14cm
A spherical air bubble in water behaves as
convex lens
concave lens
concave mirror
plane mirror
A convex lens of focal length 16cm forms a virtual image of double the size of the object. What is the distance of the object from the lens?
8cm
16 cm
24cm
32cm
Convex lens of power 4D and a concave lens of power 3D are placed in contact. What is the equivalent power of the combination?
7D
4/3 D
1D
3/4D
A biconvex lens behaves as diverging lens in water and a converging lens in air. The refractive index of water is 1.33 and that of air is 1. What can we say above the refractive index n of the material of lens?
n < 0
0<n<1
1<n<1.33
n>1.33
