Practice MCQ Questions and answers on Physics-GK

The modulus of elasticity for mild steel is approximately equal to 210 kN/mm².

The Hooke's law is valid only when the stress is proportional to the strain, that is only in the proportionality limit.

Gases are more sensitive to the temperature than liquids (such as mercury). That means gas expands more than the mercury for the same increase of temperature. Hence the gas thermometer is more sensitive than liquid (mercury) thermo-meter.

The liquid boils when the vapour pressure equals the atmospheric pressure.

Relative humidity is the ratio of the partial pressure of water vapour in an air-water mixture to the saturated vapour pressure of water at a prescribed temperature. The relative humidity of air depends not only on temperature but also on the pressure of the system of interest. If the system at State A is isobarically heated (heating with no change in system pressure) then the relative humidity of the system decreases because the saturated vapour pressure of water increases with increasing temperature.

The modulus of rigidity, also known as shear modulus, is defined as the ratio of shear stress to shear strain of a structural member. This property depends on the material of the member: the more elastic the member, the higher the modulus of rigidity.

Traditionally borax was used as a flux for brazing, but there are now many different fluxes available, often using active chemicals such as fluorides as well as wetting agents.

Physics is a complex science with several fundamental principles and laws that govern the behavior of the physical world. While there are numerous principles and equations in physics, there are four fundamental laws, also known as the "Four Fundamental Forces of Nature," that are considered the cornerstone of classical physics. These are:

1. Newton's First Law of Motion: The law of inertia.
2. Newton's Second Law of Motion: F = ma.
3. Newton's Third Law of Motion: Action and reaction are equal and opposite.
4. Law of Universal Gravitation: The force of attraction between two masses.

These laws are essential for understanding classical mechanics and are often referred to as the "laws of physics." So, the correct answer is Option B: 4, representing the four fundamental laws of physics.

Stephen Hawking is the writer of the book 'A Brief History of Time'.

'National Science Day' is celebrated in India on February 28.