Physics M.C.Q (1 Marks)

Shown in the figure here is a convergent lens placed inside a cell filled with a liquid. The lens has focal length + 20 cm when in air and its material has refractive index 1.50. If the liquid has refractive index 1.60, the focal length of the system is

A convex lens A of focal length 20 cm and a concave lens B of focal length 5 cm are kept along the same axis with the distance d between them. If a parallel beam of light falling on A leaves B as a parallel beam, then distance d in cm will be

Assertion : The cloud in sky generally appear to be whitish.
Reason : Diffraction due to cloud is efficient in equal measure at all wavelengths.

Assertion : Diamond glitters brilliantly.
Reason : Diamond does not absorb sunlight.

Assertion : The colour of the green flower seen through red glass appears to be dark.
Reason : Red glass transmits only red light.

Assertion : Different colours travel with different speed in vacuum.
Reason : Wavelength of light depends on refractive index of medium.

Assertion : The setting sun appears to be red.
Reason : Scattering of light is directly proportional to the wavelength.

Assertion : Blue colour of sky appears due to scattering of blue colour.
Reason : Blue colour has shortest wave length in visible spectrum.

Assertion : In a movie, ordinarily 24 frames are projected per second from one end to the other of the complete film.
Reason : The image formed on retina of eye is sustained upto 1/10 second after the removal of stimulus.

Assertion : The air bubble shines in water.
Reason : Air bubble in water shines due to refraction of light

Assertion : Owls can move freely during night.
Reason : They have large number of rods on their retina.

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

The refractive index of the material of the prism and liquid are 1.56 and 1.32 respectively. What will be the value of q for the following refraction

If luminous efficiency of a lamp is 2 lumen/watt and its luminous intensity is 42 candela, then power of the lamp is

To produce magnified erect image of a far object, we will be required along with a convex lens, is

The power of two convex lenses A and B are 8 diopters and 4 diopters respectively. If they are to be used as a simple microscope, the magnification of

A glass hemisphere of radius 0.04 m and R.I. of the material 1.6 is placed centrally over a cross mark on a paper
(i) with the flat face;
(ii) with the curved face in contact with the paper. In each case the cross mark is viewed directly from above. The position of the images will be

Two plane mirrors. A and B are aligned parallel to each other, as shown in the figure. A light ray is incident at an angle of 30° at a point just inside one end of A. The plane of incidence coincides with the plane of the figure. The maximum number of times the ray undergoes reflections (including the first one) before it emerges out is

A lamp rated at 100 cd hangs over the middle of a round table with diameter 3 m at a height of 2 m. It is replaced by a lamp of 25 cd and the distance to the table is changed so that the illumination at the centre of the table remains as before. The illumination at edge of the table becomes X times the original. Then X is

Five lumen/watt is the luminous efficiency of a lamp and its luminous intensity is 35 candela. The power of the lamp is

Lux is equal to

A small lamp is hung at a height of 8 feet above the centre of a round table of diameter 16 feet. The ratio of intensities of illumination at the centre and at points on the circumference of the table will be

The maximum illumination on a screen at a distance of 2 m from a lamp is 25 lux. The value of total luminous flux emitted by the lamp is

If the luminous intensity of a 100 W unidirectional bulb is 100 candela, then total luminous flux emitted from the bulb is

Total flux produced by a source of 1 cd is

"Lux" is a unit of

Assertion : The stars twinkle while the planets do not.
Reason : The stars are much bigger in size than the planets.

Assertion : A red object appears dark in the yellow light
Reason : A red colour is scattered less

The image of point P when viewed from top of the slabs will be

Two transparent slabs have the same thickness as shown. One is made of material A of refractive index 1.5. The other is made of two materials B and C with thickness in the ratio 1 : 2. The refractive index of C is 1.6. If a monochromatic parallel beam passing through the slabs has the same number of waves inside both, the refractive index of B is

A plano-convex lens when silvered in the plane side behaves like a concave mirror of focal length 30cm. However, when silvered on the convex side it behaves like a concave mirror of focal length 10 cm. Then the refractive index of its material will be

Correct exposure for a photographic print is 10 seconds at a distance of one metre from a point source of 20 candela. For an equal fogging of the print placed at a distance of 2 m from a 16 candela source, the necessary time for exposure is

In a movie hall, the distance between the projector and the screen is increased by 1% illumination on the screen is

The focal length of objective and eye lens of a microscope are 4 cm and 8 cm respectively. If the least distance of distinct vision is 24 cm and object distance is 4.5 cm from the objective lens, then the magnifying power of the microscope will be

A luminous object is placed at a distance of 30 cm from the convex lens of focal length 20 cm. On the other side of the lens, at what distance from the lens a convex mirror of radius of curvature 10 cm be placed in order to have an upright image of the object coincident with it