# May 2015

## What are transverse and longitudinal waves?

Transverse waves:   In transverse wave motion, the particles of the medium vibrate at right angles to the direction of propagation of wave. Example: Light waves are transverse waves.             Longitudinal wave motion:  In longitudinal wave motion, particles of the medium vibrate along the direction of propagation of the wave. Example: Sound waves are longitudinal waves.

## What are stationary waves?

Stationary waves:  When two simple harmonic waves of the same amplitude, frequency and time period travel in opposite directions in a straight line, the resultant wave obtained is called a stationary or a standing wave. The formation of stationary waves is due to the superposition of the two waves on the particles of the medium.

## Define wave motion?

Wave motion:  Wave motion is a form of disturbance produced in the medium by the repeated periodic motion of the particles of the medium. Here, only the waves travel forward whereas the particles of the medium vibrate about their mean positions.

## What is resonance?

Resonance:   When the forced frequency is equal to the natural frequency of vibration of the body, resonance takes place. Resonance is a vibration of large amplitude produced by a relatively small vibration near the same frequency of vibrations as the natural frequency of the resonating system.

## What are undamped free vibrations, damped free vibrations and forced vibrations?

Undamped free vibrations:  When a bob of a simple pendulum (in vacuum) is displaced from its mean position and left, it executes simple harmonic motions. The pendulum will continue to oscillate with the same time period and amplitude for any length of time. In such cases there is no loss of energy by friction or …

## What are Lissajous’ figure?

Lissajous’ figure:  When a particle is influenced simultaneously by two simple harmonic motions at right angles to each other, the resultant motion of the particle traces a curve. These curves are called Lissajous’ figure.

## What is simple harmonic motion?

Simple harmonic motion:  The type of motion where the acceleration is directed towards a fixed point (the mean position of rest) and is proportional to the displacement of the vibrating particle is called simple harmonic motion.

## What is entropy?

Entropy:  The term ‘Entropy’ is a Greek word and means transformation. Entropy is a physical property or nature of a substance that remain constant in an adiabatic process. It is a quantity that increases with the application of heat in a reversible manner. If, a process or cycle reject or absorb heat of amount dQ …

## Describe Carnot’s reversible engine.

Carnot’s reversible engine In 1824, Sadi Carnot conceived a closed reversible cycle consisting two strokes. Since that Carnot’s cycle reversible because it consists two isothermals and two adiabatic, all of which are reversible process. Carnot’s engine is free from all the defects of practical engine, its efficiency is maximum and it is an ideal heat …

## What are the postulates of the kinetic theory of gases?

Postulates of the kinetic theory of gases:  Following are the 13 postulates of kinetic theory of gases. Gas contains small individual particles called the molecules. They follow Newton’s laws of motion. The properties of the molecules of a gas are same, but different for different gases. The volume of a molecule is negligible when comparing …

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