Waves and Oscillations

Periodic Oscillations and Waves

• A periodic oscillation can be described by a wave, with examples including the motion of an object attached to a spring, which exhibits a sine wave pattern.
• The system has a natural frequency defined by its properties, including the mass of the object and stiffness of the spring.

Physical Properties of Waves

• Frequency (f) is the number of oscillations per second.
• Period (T) is the time to undergo one complete cycle.
• Wavelength (λ) is the distance traveled in one period by a moving wave.
• Amplitude is the maximum displacement from equilibrium.
• Wave speed (v) is equal to λ/T or fλ.

Types of Waves

• Longitudinal Waves: Vibrations occur in the same direction as the wave travels, with examples including sound waves.
• Transverse Waves: Vibrations occur perpendicular to the direction of the wave travel, with examples including light waves and waves on a rope.

Electromagnetic (EM) Waves

• EM waves were described by James Clerk Maxwell.
• EM waves carry or transmit energy through vacuum and matter.
• EM waves consist of oscillating electric field (E) and magnetic field (B).
• E and B are perpendicular to each other and both are perpendicular to the direction in which the wave propagates.

Properties of Electromagnetic Waves

• The speed of EM waves in air and vacuum is c = 3 × 10^8 m/s.
• EM waves can be produced by supplying an alternating current to a vertical wire (antenna), which acts as an oscillating electric dipole.
• The electromagnetic spectrum ranges from 0.03 Hz to 3 × 10^20 Hz.
• Examples of EM waves include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

Energy, Power, and Irradiance

• Energy is the ability to do work.
• Power is energy per unit time.
• Irradiance (I) is energy per unit time per unit area.

Radiation Pressure

• EM waves carry energy and momentum.
• Pressure is defined as the ratio of irradiance to the speed of light.

Polarization

• The direction of the electric field oscillation determines the polarization of the light.
• Examples of polarization include selective absorption, reflection, and molecular scattering.
• The sky appears blue due to the scattering of sunlight by air molecules.

Learn about periodic oscillations, waves, and their physical properties including frequency, period, wavelength, and amplitude.