abhinaysingh525 The splitting of different colours of light in a prism is : (1) Reflection of light (2) Dispersion of light (3) Diffraction of light (4) Refraction of light Answer: (2) The refractive index of many materials (such as glass) varies with the wavelength or colour of the light used, a phenomenon is known as dispersion. This … Read more
A boat will submerge when it displaces water equal to its own: (1) volume (2) weight (3) surface area (4) density Answer: (2) A boat will float when the weight of the water it displaces equals the weight of the boat and anything will float if it is shaped to displace its own weight of water … Read more
Surface tension in a liquid is due to : (1) Adhesive force between molecules (2) Cohesive force between molecules (3) Gravitational force between molecules (4) Electrical force between molecules Answer: (2) Surface tension is a contractive tendency of the surface of a liquid that allows it to resist an external force. This property is caused by … Read more
A circular plate, a cube and a sphere, all made up of the same material and having the same mass, are heated to 300°C and left in a room. Which of them will have the slowest rate of cooling? (1) Circular plate (2) Cube (3) Sphere (4) All will cool at the same rate Answer: (3) … Read more
Optic fibres are used in : (1) CAT scans (2) X-ray photos (3) Ultrasound scans (4) Endoscopy Answer: (4) Optical fibres are used in endoscopic instruments that enable doctors to view internal body parts without having to perform surgery. Fernando Alves Martins of Portugal invented the first fibre optic endoscope in 1963-64. Further innovations included using … Read more
Two waves, each of amplitude 1.5 mm and frequency 10 Hz, are travelling in the opposite directions with a speed of 20 mm/s. The distance in mm between adjacent nodes is : (1) 1.0 (2) 1.2 (3) 1.5 (4) 2.0 Answer: (1) Since the amplitudes, frequency and speed of both the waves are in same, hence … Read more
The snow on the mountains does NOT melt all at once when it is heated by the sun because: (1) it becomes very hard (2) it reflects most of the heat from the sun (3) it has a low specific heat capacity (4) it has a high latent heat of fusion Answer: (2) Newly formed snow … Read more
A person standing on a railway platform listens to the whistles of arriving and departing trains. The whistle heard is (1) the same in both cases in all respects (2) of higher intensity when the train arrives (3) of the higher pitch when the train arrives (4) of the higher pitch when the train departs … Read more
Holography is a technique of (1) recording a permanent, sharp two-dimensional black and white or multicolour photograph (2) recording a permanent three-dimensional multicolour photograph (3) recording a permanent three-dimensional black and white photograph (4) recording a permanent three-dimensional photograph of a given single colour or a multicolour Answer: (4) Holography is a technique that enables three-dimensional … Read more
The velocity of sound in moist air is more than in dry air because the moist air has (1) less dense than dry air. (2) less pressure than dry air. (3) more pressure than dry air. (4) more density than dry air. Answer: (1) The density of dry air is more than that of moist air … Read more