Physics Class X: Chapter 1 - Waves and Sound

Flashcards covering the vocabulary of Physics Chapter 1, including mechanics of oscillations, wave characteristics, sound reflection, and seismic phenomena.

Amplitude (a)

The magnitude of maximum displacement to one side from its equilibrium position, measured in the SI unit of metre ($m$).

Oscillation

A periodic motion in which an object moves to and fro at regular intervals of time about its equilibrium position.

Period (T)

The time taken for one oscillation, measured in seconds ($s$). Calculated as: $Period = \frac{\text{Total time}}{\text{Number of oscillations}}$.

Frequency (f)

The number of oscillations in one second, measured in hertz ($Hz$). Calculated as: $Frequency = \frac{\text{Number of oscillations}}{\text{Time}}$.

Natural frequency

The innate frequency at which an object vibrates freely, influenced by factors such as length, size, elasticity, and the nature of the material.

Forced Vibration

The vibration of an object induced by an external vibrating object.

Resonance

A phenomenon occurs when the natural frequency of the forcing object and that of the forced object are equal, causes the objects to vibrate with maximum amplitude.

Wave Motion

The continuous propagation of energy from one part to other parts through oscillations.

Electromagnetic Waves

Waves that do not require a medium for transmission, such as radio waves, microwaves, infrared rays, visible light, ultraviolet rays, $X$-rays, and gamma rays.

Mechanical Waves

Waves that require a medium for transmission, divided into longitudinal and transverse types.

Longitudinal Waves

Waves in which particles in the medium vibrate parallel to the direction of propagation, characterized by compressions and rarefactions.

Compressions (C)

Regions of high pressure in a longitudinal wave where the distance between air molecules decreases.

Rarefactions (R)

Regions of low pressure in a longitudinal wave.

Transverse Waves

Waves in which the particles of a medium vibrate perpendicular to the direction of propagation, characterized by crests and troughs.

Wavelength ($\lambda$)

The distance between two consecutive particles in the same phase of vibration, such as the distance between two consecutive crests or troughs, measured in metres ($m$).

Speed of wave

The distance travelled by a wave in one second ($m/s$). Calculated using the formula: $v = f \lambda$.

Multiple Reflection of Sound

The phenomenon where reflected sound waves are reflected again.

Echo

The sound heard after a while due to the reflection of the initial sound.

Persistence of hearing

The characteristic of the human ear where an auditory experience persists for about $1/10$ of a second.

Reverberation

The lingering of sound even after the original sound has ceased due to multiple reflection.

Limits of Audibility

The range of sound frequencies audible to a person with normal hearing, approximately between $20\,Hz$ and $20000\,Hz$ ($20\,kHz$).

Infrasonic

Sound with a frequency below $20\,Hz$.

Ultrasonic

Sound with a frequency higher than $20000\,Hz$, used in medical diagnosis, imaging, and SONAR.

Seismic Waves

Waves that travel through the Earth's crust as a result of earthquakes, volcanic eruptions, or massive explosions.

Seismology

The scientific study of seismic waves.

Richter scale

The scale used to determine the intensity of earthquakes.

Tsunami

A series of gigantic ocean waves caused by the displacement of large volumes of water, often triggered by undersea earthquakes.