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Q:

For accurate scientific work, temperatures are often measured by

A) mercury thermometers B) alcohol thermometers
C) platinum resistance thermometers D) thermoelectric thermometers

Answer:   C) platinum resistance thermometers

Explanation:

The resistance of metallic conductors e.g, platinum, increases with rise of  temperature . The increase in temperature results in a decrease of current which can be recorded in a galvanometer if the conductor is included in an electrical circuit. Thus the temperature can be known; platinum resistance thermometer is used generally for accurate scientific work. When two dissimilar metals are joined at the ends, and these ends are subjected to a difference of temperature, a current flows through the metals. Greater the difference of temperature , greater the current. So the curent strength can form the basis for measuring the difference in temperature. And when one of these temperatures is known, we can calculate the other.

Subject: Physics
Q:

The capacity of a pure capacitor is 1 farad. In D.C circuit, its effective resistance will be

A) Zero B) Infinite
C) 1 Ohm D) 1/2 Ohm
 
Answer & Explanation Answer: B) Infinite

Explanation:
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Q:

A convex mirror is used to form an image of a real object. The image

A) is diminished in size B) is erect
C) always lies between the pole and the focus D) all of the above
 
Answer & Explanation Answer: D) all of the above

Explanation:
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Q:

The quality of sound produced by an instrument depends on the

A) Frequency B) Intensity
C) Number of overtones D) None of these
 
Answer & Explanation Answer: C) Number of overtones

Explanation:
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Q:

In the electrical circuit of a house, the fuse acts as

A) a load B) a thermopile
C) a safety device D) a step down device
 
Answer & Explanation Answer: C) a safety device

Explanation:
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Q:

The direction of heat flow between two objects depends on

A) Their masses B) Their heat contents
C) Their temperatures D) Whether they are in solid, liquid or gaseous state
 
Answer & Explanation Answer: C) Their temperatures

Explanation:

Heat always flows from a body at higher temperature to a body at a lower temperature.

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