Railway Science (Physics-Waves)

It is a disturbance in matter that transfers energy through the medium. Types of mechanical wave : Transverse waves - Particles of the medium vibrate up and down perpendicular to the direction of the wave. Longitudinal waves - Particles of the medium vibrate back and forth parallel to the direction of the wave.

It is measured in hertz (Hz). The higher the frequency, the higher the pitch of the sound. Amplitude - The maximum displacement or distance moved by a point on a vibrating body or wave measured from its equilibrium position. Wavelength is the distance between two points on a wave.

A type of mechanical wave that occurs when particles of a medium (such as air, water, or solid material) move parallel to the direction of the wave propagation. Example - Sound waves in the air, Primary waves of an earthquake. In transverse waves, the displacement of the particle is perpendicular to the direction of propagation of the wave. Example - Electromagnetic waves, and Waves on a string. A stationary wave is one that is not moving or is at a standstill or resting pose.

Ultrasounds are high frequency waves. Frequencies higher than 20 kHz are called ultrasonic sound or ultrasound. Ultrasounds are able to travel along well defined paths even in the presence of obstacles. Ultrasounds are used extensively in industries and for medical purposes. Ultrasound is produced by dolphins, bats and porpoises.

The distance between two consecutive crests or troughs is called wavelength, so here wavelength will be ‘L’. Wavelength is usually denoted by the Greek letter lambda (λ). Mathematically, λ = 𝑣/𝑓 , where ‘𝑣 ’ is speed, and ‘𝑓’ is frequency.

Infrared radiation is heat energy that is emitted from all objects that have a temperature above 0 K (−273.16°C). Infrared radiation wavelengths range between 710 nm to 1 mm.

The relationship between frequency (f) and wavelength (λ) of a wave is given by the equation: v (speed of the wave) = f (frequency) × λ (wavelength) where v remains constant if the wave is in the same medium. So, if we doubled the frequency then its wavelength becomes halved.

Ultraviolet rays cover wavelengths ranging from about 4 × 10⁻⁷ m (400 nm) down to 6 × 10⁻¹⁰ m (0.6 nm). Ultraviolet (UV) radiation is produced by special lamps and very hot bodies. UV light in large quantities has harmful effects on humans. Exposure to UV radiation induces the production of more melanin, causing tanning of the skin.

Sound waves: It is a mechanical wave and needs a medium to travel. They involve particle vibration and energy transfer. Speed: Fastest in solids, then liquids, and slowest in gases. Sound can't travel in vacuum due to lack of medium.

A pulse wave or pulse train is a kind of non-sinusoidal waveform that includes square waves (duty cycle of 50%) and similarly periodic but asymmetrical waves (duty cycles other than 50%). It is also known as the rectangular wave, the periodic version of the rectangular function.