271: Which one of the following will take place when a watch based on oscillating spring is taken to a deep mine?
(a) It will become slow
(b) it will become fast
(c) It will indicate the same time as on earth
(d) It will stop working
272: Consider the following statements:
1. The albedo of an object determines its visual brightness when viewed with reflected light.
2. The albedo of Mercury is much greater than the albedo of the Earth.
Which of the statements given above is/ are correct?
(a) Neither 1 nor 2
(b) Both 1 and 2
(c) 2 only
(d) 1 only
Explanation:
The albedo of an object is the extent to which it diffusely reflects light from the sun. It is therefore a more specific form of the term reflectivity, Albedo is defined as the ratio of diffusely reflected to incident electromagnetic radiation. It is a unitless measure indicative of a surface's or body's diffuse reflectivity. The word is derived from Latin albedo "whiteness", in turn from albus "white". The range of possible values is from a (dark) to 1 (bright). The albedo of planets, satellites and asteroids can be used to infer much about their properties. The albedo of an object will determine its visual brightness when viewed with reflected light. For example, the planets are viewed by reflected sunlight and their brightness depends upon the amount of light received from the sun and their albedo. Mercury receives the maximum amount of sunlight, but its albedo is only 0.1 so it is not as bright as it would be with a higher albedo.
Geometric Albedo of Earth is 0.367 and its bond albedo is 0.29.
Geometric Albedo of Mercury is 0.138 and its bond albedo is 0.119.
273: What is the principle by which a cooling system (Radiator) in a motor car works ?
(a) Convection
(b) Conduction only
(c) Both conduction and radiation
(d) Radiation only
Explanation:
Radiators are heat exchanges used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics. The radiator is always a source of heat to its environment, although this may be either for the purpose of heating this environment, or for cooling the fluid or coolant supplied to it, as for engine cooling.
In the car, the radiator is not really a radiator, because it does not really radiate, but rather uses forces convection on two sides. In one circuit, the coolant water takes heat from the engine and delivers it to the radiator (really heat exchanger), where the heat is transferred to forced air. Both circuits used forced convection, but the heat is conducted through the tubes and fins of the radiator. There is a constraint on the max temperature of the engine, and also on the cooling water, which is related to the system pressure - one does not want the water to boil (or pressure to increase).
274: Consider the following statements:
1. The National Housing Bank, the apex institution of housing finance in India, was set up as a wholly- owned subsidiary of the Reserve Bank of India.
2. The Small Industries Development Bank of India was established as a wholly-owned subsidiary of the Industrial Development Bank of India.
Which of the statements given above is/ are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Explanation:
The National Housing Bank is wholly owned subsidiary of the RBI and the SIDBI is a subsidiary to IDBI.
275: The minimum land area recommended for forest cover to maintain proper ecological balance in India is
(a) 25%
(b) 33%
(c) 43%
(d) 53%