Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
1. Which among the following sentence is correct reason behind the blue color of ocean water?
[A] Water molecules absorb all other colors except blue
[B] Impurities in Sea water reflect the blue light
[C] Water molecules scatter the blue light
[D] None of the above
Show Answer
Correct Answer: C [Water molecules scatter the blue light]
Notes:
Water molecules scatter the blue light by absorbing the light waves and then rapidly re-emitting the light waves in different directions. That is why there are mostly blue wavelengths that are reflected back to our eyes.
2. When two mercury drops are brought into contact they form a single bigger drop to get which of the following?
[A] Minimum volume
[B] Minimum surface area
[C] Maximum size
[D] Maximum surface area
Show Answer
Correct Answer: B [Minimum surface area]
Notes:
When two drops of mercury come into contact, they will tend to merge together and form a single drop with a minimum surface area. This is because of the properties of mercury, which is a liquid metal with a high surface tension. The surface tension of a liquid is a measure of its elasticity, and it is determined by the cohesive forces between the molecules of the liquid. In the case of mercury, the high surface tension causes the molecules at the surface of the liquid to be strongly attracted to each other, which results in the formation of a relatively smooth and spherical surface. When two drops of mercury are brought together, the surface tension causes them to merge and form a single drop with the smallest possible surface area. This phenomenon is known as the “minimization of surface area” and it is a common feature of liquids with high surface tension.
3. Which frequency range characterizes Ultrasound, that is beyond the upper limit of human auditory perception?
[A] Above 20 KHz
[B] Above 200 KHz
[C] Above 2 KHz
[D] Below 20 KHz
Show Answer
Correct Answer: A [Above 20 KHz]
Notes:
Ultrasound corresponds to sound waves with frequencies exceeding the upper limit of human perceptible sound, generally above 20 kHz. Humans, typically, can perceive sounds ranging between 20 Hz and 20 kHz. Ultrasound, therefore, is beyond the auditory range of humans and is employed in technologies like medical imaging and sonar devices due to its unique properties.
4. Which among the following waves are most commonly used in the Night Vision Devices?
[A] Microwaves
[B] Infra Red Waves
[C] Ultra Violet Waves
[D] Radio Waves
Show Answer
Correct Answer: B [Infra Red Waves]
Notes:
Infrared waves are used in the night vision apparatus such as night vision goggles. Active infrared night-vision combines infrared illumination of spectral range 700–1,000 nm (just below the visible spectrum of the human eye) with CCD cameras sensitive to this light.
5. Which among the following property of the matter is studied in “Rheology”?
[A] Gravitation
[B] Viscosity
[C] Magnetic Properties
[D] Entropy
Show Answer
Correct Answer: B [Viscosity]
Notes:
Rheology is the study of the flow of matter, primarily in a liquid or gas state. It is related to Viscosity. In the science of rheology, a fluid’s changes are measured when there are actual forces (mechanical shear or pump pressure) induced.
6. A person is standing in front of a wall and makes a sound. What should be the normal minimum distance between the person and the wall , so that the person hears echo?
[A] 6 meters
[B] 13 meters
[C] 20 meters
[D] 17 meters
Show Answer
Correct Answer: D [17 meters]
Notes:
To hear an echo, the minimum distance between a wall and the source of sound is 17m. The minimum interval is 0.1 sec.
7. A piece of Ice was tied with a string to a water bucket’s bottom, and the water bucket was filled with water with ice fully submerged in it. What would be the impact on the level of water when the ice melts away completely?
[A] The level of water will go up
[B] The level of water will go down
[C] The level of water will remain unchanged
[D] The level of water will first increase then come to the previous one
Show Answer
Correct Answer: B [ The level of water will go down]
Notes:
When Ice floats in water, the level of water will remain unchanged when the ice melts away because in this situation, Ice replaced water which is “equal to its weight”. But when the floating ice is taken down in the bottom of the bucket and tied over there with a string, and let melt away, the level of water will come down because now the ice was replacing the water “equal to its volume and Ice has a lower density of water. So The answer of this question is “The level of water will go down”.
8. The magnitude of the resultant of two vectors is maximum in which of the following case?
[A] when vectors act in the same direction
[B] when vectors act in the opposite direction
[C] when vectors act at 90° to each other
[D] None of the above
Show Answer
Correct Answer: A [when vectors act in the same direction]
Notes:
The magnitude of the resultant of two vectors is maximum when vectors act in the same direction. The magnitude of the resultant of two vectors is minimum when vectors act in the opposite directions.
9. Which of the following is NOT correct about an inelastic collision?
[A] Linear momentum is conserved
[B] Kinetic energy is conserved
[C] Total energy is conserved
[D] Some or all the forces involved may be non-conservative in nature
Show Answer
Correct Answer: B [Kinetic energy is conserved]
Notes:
Following are the basic characteristics of an inelastic collision: 1. Linear momentum is conserved 2. Kinetic energy is NOT conserved 3. Total energy is conserved 4. Some or all the forces involved may be non-conservative in nature
10. What kind of energy is stored in the spring of a watch?
[A] Kinetic
[B] Potential
[C] Heat
[D] Chemical
Show Answer
Correct Answer: B [Potential]
Notes:
Potential energy is stored in the spring of a watch. Potential energy is the energy by virtue of an object’s position relative to other objects. It is often associated with restoring forces such as a spring or the force of gravity.
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