GK - Physics
11.
The snow on the mountains does not melt all at once when it is heated by the sun because:
Answer
Newly formed snow reflects about 90 per cent of the sunlight that falls upon it. This means that the sun is powerless to melt clean snow. And when snow does melt, it is not because of the sunlight. It melts because of the warm air from the sea.
Answer :
Option BExplanation :
Newly formed snow reflects about 90 per cent of the sunlight that falls upon it. This means that the sun is powerless to melt clean snow. And when snow does melt, it is not because of the sunlight. It melts because of the warm air from the sea.
12.
Rectifiers are used to convert
Answer
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.
Answer :
Option BExplanation :
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.
13.
When one enters a dark room after being in bright light one is not able to see anything clearly for a while because
Answer
The amount of light entering the eye through pupil is controlled by iris. But this adjustment takes some time. Our eyes cannot see everything clearly when we enter a dark room from a bright light. The reason for this is that in bright light the size of pupil of our eye is small. When we enter the dark room, due to small size of pupil, very little light enters our eyes. But after some time, the pupil expands and we become able to see things as more light enter our eyes.
Answer :
Option CExplanation :
The amount of light entering the eye through pupil is controlled by iris. But this adjustment takes some time. Our eyes cannot see everything clearly when we enter a dark room from a bright light. The reason for this is that in bright light the size of pupil of our eye is small. When we enter the dark room, due to small size of pupil, very little light enters our eyes. But after some time, the pupil expands and we become able to see things as more light enter our eyes.
14.
Radiocarbon dating technique is used to estimate the age of
Answer
Radiocarbon dating also referred to as carbon dating or carbon-14 dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon.
Answer :
Option DExplanation :
Radiocarbon dating also referred to as carbon dating or carbon-14 dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon.
15.
Stars appears to move from east to west because
Answer
That is due to the Earth's rotation. The Earth rotates toward the East, that makes the stars seem to move towards the West.
Answer :
Option BExplanation :
That is due to the Earth's rotation. The Earth rotates toward the East, that makes the stars seem to move towards the West.
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