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.
1. If in a closed room , the door of a refrigerator is kept open for some time , the temperature of room will ?
[A] Increase
[B] Decrease
[C] Remains same
[D] First decrease then become stable
Show Answer
Correct Answer: A [Increase]
Notes:
A refrigerator is like a heat engine. It extracts heat from low temperature reservoir and transfer it to high temperature. If a refrigerator’s door is kept open, then room will become hot, because then refrigerator exhaust more heat into the room than earlier.
2. What happens when a ship enters a Sea from a river ?
[A] It rises
[B] It remains at the same level
[C] sinks a little
[D] None of the above
Show Answer
Correct Answer: A [It rises]
Notes:
When a ship enters a sea from a river ,the ship is elevated or uplifted due to the density of sea water and during the buoyant motion of the ship, as it would gain both potential and kinetic energy when rising in the fluid.
3. What is the normal temperature of human being on Kelvin scale?
[A] 290
[B] 300
[C] 310
[D] 320
Show Answer
Correct Answer: C [310]
Notes:
The normal temperature for a human body is 310 kelvins is 36.85 degrees Celsius. The average normal body temperature is generally accepted as 98.6°F.
4. 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.
5. If earth stops rotating, the impact on weight of a body will be minimum on which among the following places?
[A] Equator
[B] North Pole
[C] Tropic of Cancer
[D] Tropic of Capricorn
Show Answer
Correct Answer: B [North Pole]
Notes:
The question is related to the centrifugal forces, which represent the effects of inertia that arise in connection with rotation and which are experienced as an outward force away from the center of rotation. The impact of this force is maximum at Equator and minimum at Pole.
6. Which among the following is the SI physical unit of dynamic viscosity?
[A] Poise
[B] Pascal-second
[C] Newton-second
[D] Poise-second
Show Answer
Correct Answer: B [Pascal-second]
Notes:
The SI unit for dynamic viscosity η is the Pascal-second (Pa-s). It corresponds to the force (N) per unit area (m2) divided by the rate of shear (s-1).
7. If a moving body turns its speed to 1.5 times, its kinetic energy __:
[A] will become 1.5 times
[B] will become 3 times
[C] will become 2.25 times
[D] will become 6 times
Show Answer
Correct Answer: C [ will become 2.25 times]
Notes:
Kinetic Energy is a product of half the Mass times Velocity Squared. When the velocity is doubled, the Kinetic energy would go up four times. If velocity is tripled, kinetic energy would go up nine times. If velocity is increased by 1.5 times the Kinetic energy would go up by 1.5×1.5=2.25 times.
8. A container is filled with water at 4°C. The water will overflow if the temperature of water is __:
[A] Increased
[B] Decreased
[C] Increased or decreased
[D] None of them
Show Answer
Correct Answer: C [ Increased or decreased]
Notes:
The reason is the anomalous expansion of water. The maximum density of water occurs at 4°C. So the water expands whether it is heated above 4°C or cooled below 4°C.
9. An Electric generator is based on which of the following scientific principles?
[A] Faraday’s law of Electromagnetic Induction
[B] Super Conductivity
[C] Laws of Thermodynamics
[D] Newton’s Law of Motion
Show Answer
Correct Answer: A [Faraday’s law of Electromagnetic Induction]
Notes:
An Electric generator works on the principle of Faraday’s law of Electromagnetic Induction. An electric generator uses mechanical energy to generate electricity applying Faraday’s law of induction. It spins a coil at a constant rate in a magnetic field to induce an oscillating emf.
10. Who among the following is credited for the discovery of ‘Expanding Universe’?
[A] Edwin Hubble
[B] Niels Bohr
[C] S Chandra Shekhar
[D] C.V Raman
Show Answer
Correct Answer: A [Edwin Hubble]
Notes:
Edwin Hubble, an american astronomer, and was the first to prove that the universe is expanding. According to Expanding Universe theory, the universe is presently expanding. Hubble proved that there is a direct relationship between the speeds of distant galaxies and their distances from Earth. This is now known as Hubble’s Law.
