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. Any moving object on earth finally comes to rest due to which among the following?
[A] Gravity
[B] Friction
[C] Inertia
[D] Motion
Show Answer
Correct Answer: B [Friction]
Notes:
Friction is the main reason for any object to come to rest. It is the main reason for the stability of the objects on earth.
2. Which among the following is true about conduction, convection and radiation mode of transfer of heat?
[A] A Medium is required for conduction but not required for convection and radiation
[B] A medium is required for conduction, convection and radiation
[C] A medium is required for conduction and convection but not required for radiation
[D] A medium is not required for conduction and convectio, radiation
Show Answer
Correct Answer: C [A medium is required for conduction and convection but not required for radiation]
Notes:
A medium is required for conduction and convection but not required for radiation. The radiation can occur even in vaccum but not the others. The conduction can travel through solid. The convection process needs liquid and gas.
3. 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.
4. Which among the following works while we wipe with a towel.?
[A] evaporation
[B] osmosis
[C] capillary action
[D] surface tension
Show Answer
Correct Answer: C [capillary action]
Notes:
Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity. The capillary action is among the following works while we wipe with a towel.
5. Which among the following provides the centripetal force to an electron circulating around the nucleus?
[A] electrostatic forces of repulsion
[B] electrostatic force of attraction
[C] speed of the electron
[D] nuclear charge
Show Answer
Correct Answer: B [electrostatic force of attraction]
Notes:
The correct answer is “electrostatic force of attraction.” In an atom, electrons are negatively charged and are attracted to the positively charged nucleus due to Coulomb’s law. This attraction provides the necessary centripetal force to keep the electron in a stable orbit around the nucleus. The balance between this electrostatic force and the electron’s inertia allows for stable atomic structures.
6. Which among the following correctly represents a Parsec?
[A] 0.326 Light Years
[B] 3.261 Light Years
[C] 32.61 Light Years
[D] 3.026 Light Years
Show Answer
Correct Answer: B [3.261 Light Years]
Notes:
One parsec is approximately equal to 31 trillion kilometres (19 trillion miles), or 210,000 astronomical units, and equates to about 3.3 light-years.
7. 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.
8. Among the following units, which one represents the smallest measurement of length?
[A] Micron
[B] Nanometer
[C] Fermi
[D] Angstrom
Show Answer
Correct Answer: C [Fermi]
Notes:
In the presented choices, the Fermi stands as the smallest unit of length measurement. It is equal to 10^-15 m. Comparatively, 1 Micron equals 10^-6 m, 1 Nanometer equals 10^-9 m, and 1 Angstrom equivalent to 10^-10 m. All these units are commonly used to measure minuscule distances, particularly in the realm of nanotechnology and particle physics. However, the Fermi, named after the esteemed physicist Enrico Fermi, remains the smallest.
9. Which of these is the cause of Friction?
[A] Roughness of surfaces in contact
[B] Force of adhesion between the molecules of the surfaces in contact
[C] Both a and b
[D] None of the above
Show Answer
Correct Answer: C [Both a and b]
Notes:
Friction is the force that opposes the relative motion between the two surfaces of objects in contact. Friction is caused due to: 1. Roughness of surfaces in contact 2. Force of adhesion between the molecules of the surfaces in contact
10. 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.
