Introduction to Waves

Waves are repeating disturbances that transfer energy through matter or space.
Waves can be classified as longitudinal or transverse based on their characteristics.

Waves differ in energy and speed.
Transverse Waves: Features crests (high points) and troughs (low points).
Longitudinal Waves: Comprised of compressions (regions where coils are close) and rarefactions (regions where coils are spread apart).

Transverse Wave: Exhibits alternating high (crests) and low (troughs) points.
Longitudinal Wave: Lacks crests and troughs, characterized instead by compressions and rarefactions.
Compression: Region where the medium’s coils are close together.
Rarefaction: Region where the medium’s coils are spread apart.

Definition: Distance between one point on a wave and the nearest similar point.
- For transverse waves: Wavelength is the distance from crest to crest or trough to trough.
- For longitudinal waves: Wavelength is the distance between two adjacent compressions or two adjacent rarefactions.

Definition: Number of wavelengths passing a fixed point each second, expressed in hertz (Hz).
For transverse waves, it can be determined by counting crests or troughs passing by a point per second.

Formula: Wave speed is calculated as
$v = f imes \lambda$ ,
where v is speed, f is frequency, and \lambda is wavelength.
Wave speed is influenced by the medium it travels through.
- Sound waves travel faster in liquids and solids compared to gases.
- Light waves travel slower in liquids and solids compared to gases or vacuum.
Speed variation with temperature: Sound waves travel faster in warmer mediums than cooler ones.

Definition: Amplitude measures the size of disturbance from a wave.
- Greater amplitude indicates a greater disturbance.
Longitudinal Wave Amplitude: Related to the compression tightness; closer coils in compressions result in greater energy.
Transverse Wave Amplitude: Distance from crest/trough to the rest position of the medium.

Incident Beam: The incoming beam striking a surface.
Reflected Beam: The beam that bounces off the surface.
Normal Line: A perpendicular line to the surface of reflection.
Angles: Angle of incidence equals angle of reflection; all reflected waves obey this law.

Definition: Bending of a wave when passing from one medium to another due to speed change.
Example: Light slows down in water, bends toward the normal when entering water from air, and bends away when transitioning back to air.

Definition: Occurs when waves change direction and bend around obstacles.
Characteristics: Transparent objects can refract light; waves can diffract when passing through narrow openings.
Wavelength Relation: The degree of diffraction depends on the size of the obstacle compared to the wavelength; smaller obstacles relative to wavelength cause more diffraction.
Example: Sound waves can diffract around doors; light waves cannot due to shorter wavelengths.

Definition: Occurs when two or more waves overlap to form a new wave.
Types of Interference:
- Constructive Interference: Crests overlap, amplifying the resultant wave’s amplitude.
- Destructive Interference: Crest of one wave meets trough of another, reducing amplitude.

Definition: Formed when two waves of equal wavelength and amplitude travel in opposite directions, causing continuous interference.
Nodes: Points where waves cancel each other out.
Example in music: Standing waves are produced in instruments like violins and flutes.

Transverse waves have alternating high points (crests) and low points (troughs).
Wavelength is the distance between one point on a wave and the nearest similar point.
Frequency refers to the number of wavelengths passing a point each second (Answer: A).
The law of reflection states the angle of incidence equals the angle of reflection.
Refraction is the bending of a wave due to speed change between mediums (Answer: C).
Hearing around corners occurs through diffraction (Answer: A).