Which of the following metals is used for the manufacture of heating elements provided in electric iron? (1) Nickel (2) Chromium (3) Nichrome (4) Tungsten Answer: (3) Nichrome is the most common domestic heating element and is found in many household products. Commonly, items such as toasters, hairdryers and heaters use nichrome coils to pass electricity … Read more
Which of the following parts of the sunlight makes the solar cooker hot? (1) Ultraviolet (2) Red light (3) Infrared (4) Cosmic rays Answer: (3) Glass transmits visible light but blocks infrared thermal radiation from escaping. This amplifies the heat-trapping effect. A solar cooker, or solar oven, is a device that uses the energy of direct … Read more
In the atmosphere ultraviolet rays are absorbed by (1) Oxygen (2) Nitrogen (3) Ozone (4) Helium Answer: (1) Most of the ultraviolet radiation in sunlight is absorbed by oxygen in Earth’s atmosphere, which forms the ozone layer of the lower stratosphere. UV light is found in sunlight (where it constitutes about 10% of the energy in … Read more
In which of the following cases, kinetic energy is being used in performing work? (1) Paddling the bicycle to cover a distance (2) Driving a car to cover a distance (3) Windmill grinding wheat grain (4) Rowing a boat in the lake Answer: (2) The work done on any object goes into changing the kinetic energy … Read more
Oil rises up the wick in a lamp because (1) Oil is very light (2) Of the diffusion of oil through the wick (3) Of the surface tension phenomenon (4) Of the capillary action phenomenon Answer: (4) It is because of the capillary action phenomenon because of which oil rises up the wick in a lamp. … Read more
Dynamo is a device for converting (1) Heat energy into electrical energy (2) Mechanical energy into electrical energy (3) Magnetic energy into electrical energy (4) Chemical energy into electrical energy Answer: (2) A dynamo is a device for converting mechanical energy into electrical energy, esp. one that produces direct current. A dynamo is an electrical generator … Read more
The sky appears blue because of (1) Atmospheric water vapour (2) Scattering of light (3) Reflection on seawater (4) Emission of blue wavelength by the sun Answer: (2), The sky is blue because the molecules in the air scatter light in the higher wavelengths (that is, the blue light), while lower wavelength light (that is, the … Read more
The energy emitted by the Sun is due to (1) Chemical reaction (2) Nuclear fission (3) Nuclear fusion (4) All of the above Answer: (3) The spectrum of the Sun’s solar radiation is close to that of a black body with a temperature of about 5,800 K. The Sun emits Electromagnetic radiation across most of the … Read more
When a vehicle passes, the TV reception gets distorted. This is because (1) metal reflects radiowaves (2) spark plug creates electromagnetic disturbances (3) vehicle pollution affects the performance of the TV components (4) modern vehicles use an electro ignition system Answer: (2) This is caused due to the interference caused by the electromagnetic waves generated by … Read more
Who measured the velocity of light first? (1) Galileo (2) Newton (3) Romer (4) Einstein Answer: (3) Galileo is often credited with being the first scientist to try to determine the speed of light. Galileo’s experiment was carried out by the Accademia del Cimento of Florence, Italy, in 1667, with the lanterns separated by about one … Read more