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Q:

A solid ball of metal has a spherical cavity inside it. When the ball is heated the volume of the cavity will

A) increase B) decrease
C) remain unaffected D) have its shape changed

Answer:   A) increase

Explanation:

The metal ball can be considered  to be made up of several layers of thinner ones. On heating each of these layers will increase in radius. As the inner most layer also increases its radius, the volume inside it i.e, the volume of the hollow portion will also increase.

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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