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1565151. If the focal length of the objective of an astronomical telescope increases, then its magnifying power will
A
Remain the same
B
Can not be predicted
C
Increase
D
DecreaseCorrect Answer: C. Increase
1602152. Which of the rays is most dangerous?
A
Gamma-ray
B
X-ray
C
Alpha ray
D
Beta rayCorrect Answer: A. Gamma-ray
1560153. A small quantity of water is placed in a small cavity made in a block ice 0°C. What will happen to the water?
A
The temperature of the water will decrease to 0°C but it will not freeze.
B
The water will freeze to ice if the block of ice is large compared to the mass of water.
C
The water will freeze to the ice at 0°C.
D
There will be no change in the temperature of the waterCorrect Answer: A. The temperature of the water will decrease to 0°C but it will not freeze.
1523154. Optical fiber works on the
A
Scattering
B
Reflection
C
Principle of Refraction
D
Total Internal ReflectionCorrect Answer: D. Total Internal Reflection
1590155. The closest distance at which a normal person can see an object clearly is
A
80 cm.
B
25 cm.
C
10 cm.
D
50 cmCorrect Answer: B. 25 cm.
1553156. Which one of the following is not an electromagnetic wave?
A
Visible light
B
Sound wave
C
Radio wave
D
X-rayCorrect Answer: B. Sound wave
1596157. Instruments can be shielded from the effects of external magnetic fields by surrounding them with
A
A brass shield
B
An iron shield
C
A glass shield
D
A rubber shieldCorrect Answer: B. An iron shield
1520158. The period of rotation of an artificial earth satellite
A
Is inversely proportional to its mass
B
24 hours
C
Depends on its distance from the earth's surface
D
Is proportional to its distance from the earth's centerCorrect Answer: C. Depends on its distance from the earth's surface
1595159. The primary colors of light are.
A
Yellow, Blue, Red, Grey.
B
Red, Blue, Green
C
Red, Green, Blue, Yellow.
D
None of the aboveCorrect Answer: B. Red, Blue, Green
1592160. The screen of the cinema hall is always white and rough. Because light rays of all colors falling on the screen suffer
A
refraction
B
scattering
C
total absorption
D
total reflectionCorrect Answer: B. scattering
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