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. 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.
2. Which among the following character of mercury makes it suitable to use in barometers instead of water?
[A] Low density and low vapor pressure
[B] High density and high vapor pressure
[C] Low density and good conductor of heat
[D] High density and low vapor pressure
Show Answer
Correct Answer: D [High density and low vapor pressure]
Notes:
Mercury is typically used in barometers because it is denser and more viscous than water, which makes it more effective at measuring changes in atmospheric pressure. It also has High density and low vapor pressure than water. When atmospheric pressure changes, the mercury in the barometer will either rise or fall in the tube, allowing the barometer to accurately measure the pressure. Additionally, mercury has a lower freezing point and a higher boiling point than water, which makes it less likely to freeze or boil at normal temperatures and therefore more reliable for use in a barometer.
3. Where will the weight of a person be maximum?
[A] At the Poles
[B] At the Tropic of Capricorn
[C] At the Tropic of Cancer
[D] At the Equator
Show Answer
Correct Answer: A [At the Poles]
Notes:
The weight of a person would be maximum at the poles, due to the higher gravitational force acting upon them in these regions. This occurs because Earth is an oblate spheroid, flattened at its poles and bulging at the equator, resulting in a shorter distance from the Earth’s center at the poles and a consequent higher gravitational pull. At the equator, the force is slightly weaker due to a greater distance from the Earth’s center. Weights at the Tropics of Cancer and Capricorn lie in-between the poles and equator, but are closer to the equator’s value.
4. Which among the following temperature scale is based upon absolute zero?
[A] Celsius
[B] Fahrenheit
[C] Kelvin
[D] Rankine
Show Answer
Correct Answer: C [Kelvin]
Notes:
Kelvin is the base unit of temperature (SI unit), having the unit symbol K. The Kelvin temperature scale has an absolute zero (0°K) below which temperatures do not exist. It is the lowest possible temperature. At this temperature there is no motion and no heat. It is equivalent to 0°K, or -273.15° C, or at -460° F.
5. If a moving body turns its speed to 1.5 times, what will be the impact on 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.
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. While passing over an obstacle a light ray slightly bends round the corner. The phenomenon is known as__:
[A] Scattering
[B] Polarisation
[C] Diffraction
[D] Refraction
Show Answer
Correct Answer: C [ Diffraction]
Notes:
The phenomenon of light rays bending around the corners of obstacles is called diffraction. Diffraction refers to various phenomena that occur when a wave encounters an obstacle or a slit.
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 the following is true about displacement of an object?
[A] It is always equal to the distance travelled by the object
[B] It can be less than the distance travelled by the object
[C] It can be greater than the distance travelled by the object
[D] It always less than the distance travelled by the object
Show Answer
Correct Answer: B [It can be less than the distance travelled by the object]
Notes:
The displacement is the shortest distance between the initial and final position of an object in the given time. The displacement of an object is a vector quantity. It can be less than or equal to the distance but can never be greater than the distance travelled by that object
10. What is the slope of the velocity-time graph when an object moves with constant negative acceleration, having positive initial velocity?
[A] 90°
[B] more than 90°
[C] less than 90°
[D] 0°
Show Answer
Correct Answer: B [more than 90°]
Notes:
When an object moves with constant negative acceleration, having positive initial velocity, the velocity-time graph is a straight line having slope more than 90°. When an object moves with constant positive acceleration, having positive initial velocity, the velocity-time graph is a straight line having slope less than 90°.