A spherical surface of radius of curvature R separates air (refractive index 1.0) from glass (refractive index 1.5). The centre of curvature is in the glass. A point object P placed in air is found to have a real image Q in the glass. The line PQ cuts the surface at a point O, and PO = OQ. The distance PO is equal to
5R
3R
2R
1.5R
In young’s double-experiment, the separation between the slits is halved and the distance between the slits and the screen is doubled. The fringe width is
Unchanged.
halved
doubled
quadrupled
Yellow light is used in a single slit diffraction experiment with slit width of 0.6 mm. If yellow light is replaced by X- rays, then the observed pattern will reveal.
That the central maximum is narrower
More number of fringes
Less number of fringes
No diffraction pattern
In the ideal double-slit experiment, when a glass-plate (refractive index 1.5) of thickness t is introduced in the path of one of the interfering beams (wave-length (), the intensity at the position where the central maximum occurred previously remains unchanged. The minimum thickness of the glass-plate is
2(
2( /3
( /3
(
The size of the image of an object, which is at infinity, as formed by a convex lens of focal length 30 cm is 2 cm. If a convex lens and focal length 20 cm is placed between the convex lens the image at a distances of 26 cm from the convex lens. Calculate the new size of the image.
1.25 cm
2.5 cm
1.05 cm
2 cm
A point object is placed at the centre of a glass sphere of radius 6 cm and refractive index 1.5. The distance of virtual image from the surface is
6 cm
4 cm
12 cm
9 cm
In Young’s double slit experiment intensity at a point is (1/4) of the maximum intensity. Angular position of this point is
sin-1 ((/d)
sin-1 ((/2d)
sin-1 ((/3d)
sin-1 ((/4d)
A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is
-1.5 dioptres
-6.5 dioptres
+6.5 dioptres
+6.67 dioptres
A thin prism P1 with angle 4o and made from glass of refractive index 1.54 is combined with another thin prism P2 made from glass of refractive index 1.72 to produce dispersion without deviation. The angle of the prism P2 is
5.33o
4o
3o
2.6o
A real image of a distant object is formed by a plano-convex lens on its principal axis. Spherical aberration
Is absent
Is smaller if the curved surface of the lens faces the object
Is smaller if the plane surface of the lens faces the object
Is the same whichever side to the lens faces the object