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Q:

When one enters a dark room after being in bright light one is not able to see anything clearly for a while because 

A) the retina of the eye moves forward B) the retina of the eye moves backward
C) the iris is unable to dilate the pupil immediately to be able to see things D) the eye has no power of accommodation

Answer:   C) the iris is unable to dilate the pupil immediately to be able to see things

Explanation:

The size of the pupil of the automatically adjusts itself according to the intensity of light passing through it; if the intensity is more, the size is less, if less, it is more. So in our case the pupil should dilate i.e , increase in size to be able to see in the dark. This switchover takes some time. But here the entry into the dark room is immediate. So the eye has no time to adjust itself and hence is not able to see at all for a while. 

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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