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
When a ring of metal is heated what happens to its hole? (1) expands (2) contracts (3) it expands or contracts according to its diameter (4) it expands or contracts according to its coefficient of expansion Answer: (1) The hole size will increase because in expansion the size between two molecules do not increase so when … 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
Which among the following is the fundamental quantity? (1) Volume (2) Time (3) Velocity (4) Force Answer: (2). The fundamental qualities of Physics are the seven basic quantities that can be used to express all other physical quantities. These are as follows: Length: Metre, Heat: Kelvin, Time: second, Luminous Intensity: Candela, Mass: Kilogram, Electric Current: Ampere, … 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
The dimension of which of the following is the same as that of impulse? (1) Volume (2) Momentum (3) Torque (4) Change in the rate of momentum Answer: (2) The quantity of impulse is force × time interval. In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an … Read more
In a refrigerator what produces the cooling? (1) The ice which deposits on the freezer (2) The sudden expansion of a compressed gas (3) The evaporation of a volatile liquid (4) None of these Answer: (4) Basically, a refrigeration system consists of devices that compress and expand refrigerant gas. When refrigerant gas is compressed it expels … Read more
The different colours of different stars are due to the variation of (1) temperature (2) pressure (3) density (4) radiation from them Answer: (1). Shortly after blackbody radiation was understood, it was noticed that the spectra of stars look extremely similar to blackbody radiation curves of various temperatures, ranging from a few thousand Kelvin to ~50,000 … Read more
Coolis tube is used to produce (1) Radio waves (2) Microwaves (3) X-rays (4) Gama rays Answer: (3) X-rays are part of the electromagnetic spectrum, ionizing radiation with wavelengths shorter than ultraviolet light. X-ray tubes evolved from experimental Crookes tubes with which X-rays were first discovered in the late 19th century, and the availability of this … Read more
Clothes keep us warm in winter because they : (1) supply heat (2) do not radiate heat (3) prevent air from contacting the body (4) prevent the heat of the body from escaping Answer: (4) It is just because woollen clothes have fibres and between those fibres air is trapped which reduces heat loss. Air reduces … Read more