Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
11. Which of the following is true about the effect of altitude on the value of acceleration due to gravity?
[A] The acceleration due to gravity decreases with height
[B] The acceleration due to gravity increases with height
[C] The acceleration due to gravity is not dependent on height
[D] None of the above
Show Answer
Correct Answer: A [The acceleration due to gravity decreases with height]
Notes:
The acceleration due to gravity decreases with height. G0= g(1-2h/R) where h is the height above the surface of the earth.
12. What will be the effect on the value of acceleration due to gravity at the poles if the rate of rotation of earth increases?
[A] No effect
[B] it will increase
[C] it will decrease
[D] it will become zero
Show Answer
Correct Answer: A [No effect]
Notes:
If the rate of rotation of earth increases then the value of acceleration due to gravity decreases at all the places on the surface of earth except at poles.
13. Two satellites, A having mass of 500 kgs and B having mass of 1200 kgs, are launched from earth. Which of these will have a greater orbital velocity if the radius of orbit is same for both?
[A] Satellite A
[B] Satellite B
[C] Both satellites will have the same orbital velocity
[D] Cant be determined
Show Answer
Correct Answer: C [Both satellites will have the same orbital velocity]
Notes:
Both satellites will have the same orbital velocity as the orbital velocity of a satellite is independent of mass of satellite.
14. Which of the following equation represents the Torricelli’s law?
[A] (2gh)1/2
[B] √3 gh
[C] √2 gh
[D] 2gh
Show Answer
Correct Answer: A [(2gh)1/2]
Notes:
Torricelli’s theorem is also called as Torricelli’s law, It states that the speed, v, of a liquid flowing under the force of gravity out of an opening in a tank is proportional jointly to the square root of the vertical distance, h, between the liquid surface and the centre of the opening and to the square root of double the acceleration due to gravity. V = (2gh)1/2
15. What is the upward force experienced by a body, when it is immersed in a fluid, known as?
[A] Tangential force
[B] Buoyant force
[C] Centrifugal force
[D] Hydraulic force
Show Answer
Correct Answer: B [Buoyant force]
Notes:
When a body is immersed in a fluid (liquid or gas) it exerts an upward force on that body. This upward force is called up thrust or buoyant force, The whole phenomenon is called as buoyancy.
16. Which of the following is the S.I. unit of density?
[A] m-2
[B] m-3
[C] kg m-2
[D] kg m-3
Show Answer
Correct Answer: D [ kg m-3 ]
Notes:
The SI unit of density is kg m-3. It is a positive scalar quantity. The Gaussian unit of density is the gram per cubic centimeter which is equivalent to a gram per milliliter [1 g/cm3 = 1 g/ml].
17. What happens to the time period of the simple pendulum if the solid bob is replaced by a hollow sphere of same radius but half the mass?
[A] time period becomes double
[B] time period remains unchanged
[C] time period becomes half
[D] time period becomes four times
Show Answer
Correct Answer: B [time period remains unchanged]
Notes:
Time period of simple pendulum is independent of mass of the bob. Therefore, If the solid bob is replaced by a hollow sphere of same radius but different mass, time period remains unchanged.
18. What is the effect of rise of temperature on the time period of a simple pendulum?
[A] it increases
[B] it decreases
[C] it may or may not increase
[D] No relationship
Show Answer
Correct Answer: A [it increases]
Notes:
If the bob of simple pendulum is suspended by a wire then effective length of pendulum will increase with the rise of temperature due to which the time period will increase.
19. Which of the following electromagnetic waves are produced due to the radioactive decay of the nucleus?
[A] X-rays
[B] Gamma rays
[C] Radio waves
[D] UV rays
Show Answer
Correct Answer: B [Gamma rays]
Notes:
Gamma rays are produced due to the radioactive decay of the nucleus. Gamma rays have wavelength less than 10–3 nm.
20. Which of the following electromagnetic waves in the EM spectrum has the highest wavelength?
[A] X-rays
[B] Visible
[C] Infrared
[D] UV-rays
Show Answer
Correct Answer: C [Infrared]
Notes:
The electromagnetic spectrum when arranged from longest wavelength to shortest includes radio waves, microwaves, infrared, optical, ultraviolet, X-rays, and gamma-rays.
