Physics MCQs

Notes:
A concave lens is a type of lens that has a thinner center than edges, and it is sometimes called a diverging lens because it spreads out light rays that are parallel to its axis. The focal length of a lens is a measure of its ability to focus light, and it is defined as the distance from the lens to the point where the light rays converge. In the case of a concave lens with a power of -5D, the focal length would be equal to 1/5 of a meter, or 20 centimeters.

Notes:
Scattering of light is the phenomenon in which light rays get deviated from its straight path on striking an obstacle.The scattering of light can be of many reason. Some of them are dust, smoke and gas molecules.

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.

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.

Notes:
J.J Thompson was the first scientist to discover and identify the electrons and to make the discovery of the first subatomic particle. He was also the first scientist to find evidence for isotopes of a stable (non-radioactive) element in 1913, as part of his exploration into the composition of canal rays (positive ions). His experiments to determine the nature of positively charged particles led to the development of the mass spectrograph. J.J Thompson belonged to United Kingdom. He won the Nobel Prize in Physics in 1906 for his work on the conduction of electricity in gases.

Notes:
When one body is actually moving over the surface of other body, the friction is known as Kinetic friction. It is also known as dynamic friction.

Notes:
Joule is the absolute unit of work in S.I 1 joule = 1 Nm

• 1 joule= 10⁷ ergs (erg is the unit of work in c.g.s)
• 1 erg = 1 dyne cm
• Also, Kilogram-metre (kg-m) is the gravitational unit of work on S.I 1 kg-m = 9.8 j

Notes:
The universal gravitational constant is equal to the force of attraction between two bodies each of unit mass having their centres placed at unit distance apart. F = Gm₁m₂/r When m₁ and m₂ = 1 and r=1 then F=G.

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.

Notes:
The unit of intensity of Gravitational field in the c.g.s system is dyne g^-1 or cm s^-2. S.I. unit of intensity of Gravitational field is N Kg^-1 m s^-2.