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 of the following statements is incorrect about a Plane Mirror?
[A] The focal length of a plane mirror is infinity
[B] Its optical power is one
[C] It forms a virtual image of a real object
[D] It is used in constructing periscope
Show Answer
Correct Answer: B [Its optical power is one]
Notes:
Second statement is incorrect because the optical power of plane mirror is zero.
2. When a tubelight breaks, a cracking sound is produced because ____?
[A] Pressure inside the lamp is less than atmospheric pressure
[B] Pressure inside the lamp is more than atmospheric pressure
[C] The lamp is filled with reactive gases
[D] The lamp is filled with mercury vapour
Show Answer
Correct Answer: A [Pressure inside the lamp is less than atmospheric pressure ]
Notes:
A fluorescent lamp tube is filled with a gas containing low pressure mercury vapor and argon, xenon, neon, or krypton. The pressure inside the lamp is around 0.3% of atmospheric pressure.
3. A vehicle moving on a circular path experiences ________?
[A] centripetal force
[B] centrifugal force
[C] gravitational force
[D] None of the above
Show Answer
Correct Answer: A [centripetal force]
Notes:
A vehicle moving on a circular path experiences centripetal force. Centripetal force that acts on a body moving in a circular path and is directed towards the centre around which the body is moving.
4. Due to which of the following phenomena, the coloured glass appears white when crushed into fine powder?
[A] Total Internal Reflection
[B] Diffraction
[C] Scattering
[D] Refraction
Show Answer
Correct Answer: C [ Scattering]
Notes:
When the glass is crushed into fine powder the light incident is totally scattered without the absorption so due to the composite light crushed glass appears white.
5. Which of the following is/are independent of mass during the projectile motion?
[A] Time of Flight
[B] Horizontal Range
[C] Maximum Height
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
The Time of Flight, Horizontal Range and the Maximum Height of an object are independent of mass of the object during the projectile motion.
6. The Universal Gravitational Constant for two bodies is dependent on which of the following?
[A] Nature of the bodies
[B] Size of the bodies
[C] Nature of medium between the bodies
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:
The value of Universal Gravitational Constant is same throughout the universe. It is independent of nature of the bodies, size of the bodies and nature of medium between the bodies.
7. Which of the following is correct about Gravitational force?
[A] It is always attractive in nature
[B] It is always repulsive in nature
[C] It may or may not be attractive in nature
[D] None of the above
Show Answer
Correct Answer: A [It is always attractive in nature]
Notes:
The Gravitational force is always attractive in nature while electric and magnetic force can be attractive or repulsive. It is the weakest force in nature.
8. Which of the following is the orbital velocity of a satellite orbiting very close to the surface of earth?
[A] 7.92 km/s
[B] 9.8 km/s
[C] 11.2 km/s
[D] 14.8 km/s
Show Answer
Correct Answer: A [7.92 km/s]
Notes:
In this case, the radius of the orbit will be nearly equal to the radius of earth. The orbital velocity of a satellite orbiting very close to the surface of earth is 7.92 km/s.
9. What is the orbital velocity of geo stationary satellite?
[A] 4.15 km/s
[B] 2.78 km/s
[C] 3.08 km/s
[D] 6.66 km/s
Show Answer
Correct Answer: C [3.08 km/s]
Notes:
Orbital velocity of geo stationary satellite can be calculated as (GM/r)1/2. The orbital velocity of geo stationary satellite is 3.08 km/s.
10. What is the escape velocity of a planet having mass 6 times and radius 2 times as that of earth?
[A] 3 ve
[B] √2 ve
[C] √3 ve
[D] 2 ve
Show Answer
Correct Answer: C [√3 ve]
Notes:
Escape velocity of a satellite is given by ve = (2GM/r)1/2 So when M=6times and R=2R, then ve becomes √3 ve.
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