UPSC  Physics

101. Consider the following statements:
1. If magenta and yellow coloured circles intersect, the intersected area will have red colour.
2. If cyan and magenta coloured circles intersect, the intersected area will have blue colour.
Which of the statements given above is/are correct?

1 only 2 only Both 1 and 2 Neither 1 nor 2

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102. Consider the following statements:
1. A flute of smaller length produces waves of lower frequency.
2. Sound travels in rocks in the form of longitudinal elastic waves only.
Which of the statements given above is/are correct?

1 only 2 only Both 1 and 2 Neither 1 nor 2

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103. Assertion (A): A jet aircraft moving at Mach Number equal to 1 travels faster at an altitude of 15 km than while moving at Mach Number equal to 1 near the sea level.
Reason (R): The velocity of sound depends on the temperature of the surrounding medium.

Both A are R are true and R is the correct explanation of A Both A and R are true but R is not a correct explanation of A A is true but R is false A is false but R is true

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104. Consider the following phenomena:
1. Size of the sun at dusk.
2. Colour of the sun at dawn
3. Moon being visible at dawn
4. Twinkle of stars in the sky
5. Polestar being visible in the sky
Which of the above are optical illusions?

1, 2 and 3 3, 4 and 5 1, 2 and 4 2, 3 and 5

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105. Rainbow is produced when sunlight falls on drops of rain. Which of the following physical phenomena are responsible for this?
1. Dispersion
2. Refraction
3. Internal reflection
Select the correct answer using the codes below.

1 and 2 only 2 and 3 only 1 and 3 only 1, 2 and 3

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106. During a thunderstorm, the thunder in the skies is produced by the
1. meeting of cumulonimbus clouds in the sky
2. lightning that separates the nimbus clouds
3. violent upward movement of air and water particles
Select the correct answer using the codes given below.

1 only 2 and 3 1 and 3 None of the above produces the thunder

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107. A fuse is used in mains electric supply as a safety device. Which one of the following statements about the fuse is correct?

It is connected in parallel with the main switch It is made mainly from silver alloys It must have a low melting point It must have very high resistance

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108. Consider the following statements:
An ordinary light bulb has a rather short life because the:
1. filament wire is not uniform.
2. bulb cannot be evacuated completely.
3. wires supporting the filament melt at high
temperatures.
Which of the above statements are correct?

1 and 3 2 and 3 1 and 2 1, 2 and 3

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109. Consider the following statements regarding a motor car battery:
1. The voltage is usually 12 V.
2. Electrolyte used is hydrochloric acid.
3. Electrodes are lead and copper.
4. Capacity is expressed in ampere-hour.
Which of the above statements are correct?

1 and 2 2 and 3 3 and 4 1 and 4

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110. Assertion (A): In our houses, the current in A.C. electricity line changes direction 60 times per second.
Reason (R): The frequency of alternating voltage supplied is 50 Hz.

Both A and R are individually true and R is the correct explanation of A Both A and R are individually true but R is not the correct explanation of A A is true but R is false A is false but R is true

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