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 explains the radiation emitted by black bodies?
[A] Big-bang theory
[B] Quantum Theory
[C] Piezoelectric Effect
[D] None of the above
Show Answer
Correct Answer: B [Quantum Theory]
Notes:
The correct answer is Quantum Theory. Black body radiation refers to the electromagnetic radiation emitted by an idealized object that absorbs all incident radiation. Max Planck introduced the concept in 1900, leading to the development of quantum mechanics. This theory explains that energy is quantized, emitted in discrete packets called quanta or photons, resolving the ultraviolet catastrophe predicted by classical physics.
2. A small quantity of water is placed in a small cavity made in a block of Ice at 0 degree centigrade. Which of the following will happen?
[A] the temperature of water will become zero and it will freeze
[B] the temperature of water will become zero but it will not freeze
[C] the temperature of the water will become zero and it will come out of the cavity
[D] the temperature of the water will become zero and ice will melt to merge with water
Show Answer
Correct Answer: B [the temperature of water will become zero but it will not freeze]
Notes:
When a small quantity of water is placed in a small cavity made in a block of Ice at 0 degree centigrade the temperature of water will become zero but it will not freeze.
3. The term “Isopycnic” is most closely defined by which among the following?
[A] Two places with same atmospheric pressure
[B] Two liquids with same viscosity
[C] Two liquids with same density
[D] Two places with same temperature
Show Answer
Correct Answer: C [Two liquids with same density]
Notes:
The term “Isopycnic” refers to two substances having the same density. It is derived from the Greek words “iso,” meaning equal, and “pycnos,” meaning dense. In scientific contexts, isopycnic conditions are often used in centrifugation techniques to separate particles based on their density, such as in the purification of DNA or proteins.
4. One joule of work is said to be done when__:
[A] a force of 1 dyne causes a displacement of 1 cm.
[B] a force of 1 dyne causes a displacement of 1 m.
[C] a force of 1 N causes a displacement of 1 cm.
[D] a force of 1 N causes a displacement of 1 m.
Show Answer
Correct Answer: D [ a force of 1 N causes a displacement of 1 m.]
Notes:
The joule is the unit of energy in the International System of Units. It is equal to the work done on an object when a force of one Newton acts on that object in the direction of the force’s motion through a distance of one meter. One joule of work is said to be done when a force of 1 N causes a displacement of 1 m.
5. A cardboard is placed on a glass of water, and a ten paise coin is placed on the cardboard. If the cardboard is flicked suddenly in the direction parallel to its surface, then the cardboard flies away, but the coin falls in the glass.
The behaviour of the coin can be explained by which among the following properties?
[A] Momentum
[B] Acceleration
[C] Inertia
[D] Friction
Show Answer
Correct Answer: C [ Inertia]
Notes:
Inertia is the property of matter that is why it continues in its existing state of either rest or motion. It can be changed by an external force. Here in the question the coin falls in the glass even after the cardboard is flicked because it maintains its rest position by the nature of inertia.
6. Which among the following provides potential energy to an object?
[A] Its momentum
[B] It’s position
[C] It’s acceleration
[D] It’s shape
Show Answer
Correct Answer: B [ It’s position]
Notes:
The potential energy is defined as the energy that is stored in an object due to its position. Various types of potential energy include the gravitational potential energy (depends on its mass and its distance from the center of other object’s mass), the elastic potential energy, the electric potential energy.
7. The frequency range of Ultra High Frequency (UHF) is __?
[A] 3 to 10 Megahertz
[B] 3 to 30 Megahertz
[C] 300 to 3000 Megahertz
[D] 300 to 30000 Megahertz
Show Answer
Correct Answer: C [ 300 to 3000 Megahertz]
Notes:
Ultra High Frequency (UHF) designates the ITU radio frequency range of electromagnetic waves between 300 Megahertz to 3 GHz (3,000 Megahertz).
8. A person weighing 80 Kg. is standing on an accurate scale in an elevator. The elevator is slowing down while moving downwards. In this case the scale will read__?
[A] 80 Kg.
[B] Less than 80 Kg
[C] More than 80 Kg
[D] Either less or more than 80 Kg
Show Answer
Correct Answer: C [More than 80 Kg]
Notes:
When the elevator is slowing down while moving downwards, that means there is an acceleration upwards. The gravitational force must be lesser than the normal force. Thus, during slowing down while moving downwards, the normal force on the feet of a passenger is greater than her weight. In this case the scale will read more than 80 kg.
9. Who among the following is credited to work for the unification of electricity, magnetism and optics field of Physics?
[A] James Clerk Maxwell
[B] Michael Faraday
[C] Haris Christian Oersted
[D] Isaac Newton
Show Answer
Correct Answer: A [James Clerk Maxwell]
Notes:
James Clerk Maxwell made the efforts for the unification of electricity, magnetism and optics field of Physics. He showed that light is an electromagnetic wave. James Clerk Maxwell was a Scottish mathematician, physicist and is known best for his mathematical work on electromagnetism and on the behaviour of gases.
10. What is the S.I. unit for Luminous Intensity?
[A] mole
[B] ampere
[C] candela
[D] weber
Show Answer
Correct Answer: C [ candela ]
Notes:
The S.I. unit for Luminous Intensity is candela. The symbol used for candela is cd. Mole is the S.I unit for Quantity of Matter ampere is the S.I unit for Electric Current. Weber is the S.I unit for Magnetic Flux Luminous Intensity is the amount of light that a point source radiates in a given direction
