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. 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.
2. 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.
3. When a barometer is taken down in a coal mine , which of the following happens with the Mercury level in the tube?
[A] rises
[B] falls
[C] falls then rises
[D] remains unaltered
Show Answer
Correct Answer: A [rises]
Notes:
When a barometer is taken down into a coal mine, the mercury level rises. This is because the temperature increases as you move down the Earth’s crust. There is also very little wind, so the warmth can’t distribute the temperature and moderate it. A barometer is an instrument that measures pressure. In a coal mine, the pressure is higher than normal pressure. When a barometer is taken down into a coal mine, it shows a greater reading.
4. 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.
5. If the distance between the earth and the sun becomes one-fourth of what it is now, the gravitational force exerted on the earth by the sun would be:
[A] One-fourth of what it is now
[B] One-sixteenth of what it is now
[C] Sixteen times of what it is now
[D] Four times of what it is now
Show Answer
Correct Answer: C [ Sixteen times of what it is now]
Notes:
Gravitational force is inversely proportional to the square of the distance between the bodies.
6. Two pieces of ice at 0°C would freeze together if pressed against each other and then released. In this context, which among the following is the correct principle in action in this?
[A] The melting point of pure ice decreases with pressure.
[B] The melting point of pure ice increases with Pressure
[C] The melting point of pure ice first increases, then decreases with pressure
[D] The melting point of pure ice first decreases then increases with pressure
Show Answer
Correct Answer: A [ The melting point of pure ice decreases with pressure.]
Notes:
Melting point of pure ice decreases with pressure at the rate of 0.0072°C per atmosphere and this is called regulation, which was discovered by Faraday and occurs at some 0°C or very slightly less temperature.
7. Who among the following is credited for the Corpuscular theory of light?
[A] Isaac Newton
[B] Christiaan Hyugens
[C] Albert Einstein
[D] James Clerk Maxwell
Show Answer
Correct Answer: A [Isaac Newton]
Notes:
The Corpuscular theory of light was given by Isaac Newton. It was replaced by Huygens’ wave theory when it failed to adequately explain the diffraction, interference and polarization of light. The Huygens’ wave theory was replaced by Planck’s quantum theory and finally de-Broglie’s Dual-Theory of light replaced all previous ones.
8. 1 nautical mile is equivalent to which of the following?
[A] 1.44 x 1000 m
[B] 1.852 x 100 m
[C] 1.852 x 1000 m
[D] 1.44 x 100 m
Show Answer
Correct Answer: C [ 1.852 x 1000 m ]
Notes:nautical mile is a unit of length. 1 nautical mile is equal to 1.852 x 1000 m Other important units of length are:
- 1 mile = 1.609 x 1000 m
- 1 light year = 9.46 x 1015 m
- 1 AU = 1.5 x 1011m
- 1 Par sec = 3.1 x 1016m
9. Joule/kg is the S.I unit of which of these physical quantities?
[A] Entropy
[B] Permittivity of free space
[C] Latent heat
[D] Gas constant
Show Answer
Correct Answer: C [ Latent heat ]
Notes:
Joule/kg is the S.I unit of Latent heat Latent heat(L) = heat(Q)/mass(m) Latent heat is the heat required to convert a solid into a liquid or vapor, or a liquid into a vapor, without any change in temperature. Unit of Entropy: J/K Unit of Permittivity of free space: H/m Unit of Gas constant : J/K
10. Which of these pairs has the same unit of measurement?
[A] Rate of flow and Acceleration
[B] Impulse and Moment of Force
[C] Rydberg constant and Gas constant
[D] Pressure and Coefficient of Elasticity
Show Answer
Correct Answer: D [ Pressure and Coefficient of Elasticity ]
Notes:
Pressure and Coefficient of Elasticity have the same unit i.e. N m-2 (Newton per metre square) Other important units: Rate of Flow: m3s-1 Acceleration: ms-2 Rydberg constant: 1/m Gas constant: J/K Impulse: Ns Moment of Force: Nm
