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. A transition from the solid to gas phase with no intermediate liquid stage is called?
[A] Evaporation
[B] Sublimation
[C] Adsorption
[D] Solid Phase extraction
Show Answer
Correct Answer: B [Sublimation]
Notes:
Sublimation is the process by which a substance transitions from a solid to a gas without passing through a liquid phase. This typically occurs when a substance is heated to a temperature at which its solid form becomes a gas, such as when dry ice (solid carbon dioxide) sublimates and turns into gas. Sublimation can also occur when a substance is exposed to a vacuum, which can cause gases to be drawn out of the substance and turn into a solid. Sublimation is an important process in many scientific and industrial fields, including meteorology, chemistry, and materials science. Camphor is also an example of Sublimation.
3. Mach number is a measure of which of the following?
[A] Speed
[B] Heat Transfer
[C] Static Pressure
[D] Volume
Show Answer
Correct Answer: A [Speed]
Notes:
Mach number refers to the ratio of the velocity of a fluid to the velocity of sound in that fluid, named after Ernst Mach (1838–1916), an Austrian physicist and philosopher. Speed of sound is Mach 1 speed.
4. Which among the following strictly works on the principle of dipole movement of the water molecules?
[A] Refrigerator
[B] Microwave Oven
[C] Air Conditioner
[D] Electric Geyser
Show Answer
Correct Answer: B [Microwave Oven]
Notes:
Microwave Oven strictly works on the principle of dipole movement of water molecule. A microwave oven is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range.
5. “Fermi” is a unit of which among the following?
[A] Mass
[B] Length
[C] Velocity
[D] Frequency
Show Answer
Correct Answer: B [Length]
Notes:
“Fermi” is the unit of length. The femtometre is an SI unit of length equal to 10⁻¹⁵ metres, which means a quadrillionth of one.
6. For any object on the surface of earth, which among the following properties will be directly proportional to each other?
[A] It’s acceleration and it’s mass
[B] It’s mass and it’s weight
[C] It’s weight and it’s acceleration
[D] It’s speed and it’s velocity
Show Answer
Correct Answer: B [ It’s mass and it’s weight]
Notes:
The weight of an object and its mass are directly proportional. For a given gravitational field strength, the greater the mass of the object, the greater its weight.
7. 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.
8. 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.
9. Which of the following is the unit of Velocity Gradient?(s=second)
[A] s2
[B] s-1
[C] s
[D] s-2
Show Answer
Correct Answer: B [ s-1 ]
Notes:
The unit of Velocity Gradient is s-1(per second) Velocity Gradient = Velocity/time Velocity gradient shows that how the velocity of a fluid changes between different points within the fluid.
10. The centripetal force and centrifugal force are ______:
[A] equal in magnitude and have same direction
[B] unequal in magnitude and have same direction
[C] equal in magnitude and have opposite direction
[D] unequal in magnitude and have opposite direction
Show Answer
Correct Answer: C [equal in magnitude and have opposite direction]
Notes:
The centripetal force and centrifugal force are equal in magnitude and have opposite direction. Centrifugal force can be regarded as the reaction of centripetal force.
