Fundamentals of Mechanical and Electromagnetic Waves

Fundamentals of Waves: Chapters 14 & 16

Mechanical vs. Electromagnetic Waves

Waves are broadly classified based on their requirement for a medium to travel:

Mechanical Waves

Mechanical waves require a medium (such as air, water, or solids) to travel.

• Examples: Sound waves, ocean waves, and waves traveling through springs.

Electromagnetic Waves (EM Waves)

Electromagnetic waves do not require a medium to travel; they can propagate through a vacuum.

• Examples: Radio waves, microwaves, infrared radiation, visible light, X-rays, and gamma rays.

Transverse Waves vs. Longitudinal Waves

Longitudinal Waves

In longitudinal waves, particles vibrate along the wave direction (parallel to propagation).

• Examples: Sound waves and waves in springs (compressions and rarefactions).

Transverse Waves

In transverse waves, particles vibrate at a right angle (perpendicular) to the wave direction.

• Examples: All electromagnetic waves and surface water waves.

Labeling Wave Types

The Electromagnetic Spectrum

The electromagnetic spectrum encompasses all forms of electromagnetic radiation, ranging from radio waves to gamma rays (which are high-energy forms of light).

Properties of Electromagnetic Waves

• They travel at the speed of light in a vacuum.
• They include ultraviolet (UV) waves.
• They can transfer energy through empty space.

Uses of Electromagnetic Waves in Daily Life

The spectrum includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Gamma rays have specific uses:

• Killing living organisms (sterilization).
• Sterilizing medical equipment.
• Treating cancer.
• Taking images using radioactive tracers.

Physics Concepts Review

Static Electricity and Grounding

Fill in the blank:

When cars run, their tires and bodies are usually charged by friction. For a gasoline tanker, if the accumulated charge is large enough, sparks can be produced and an explosion will occur if gasoline vapor is ignited. Metal chains at the back of the tankers conduct the bodies of tankers to the ground to avoid the danger. The above process is known as earthing/grounding.

Key Definitions

1. The maximum displacement of a wave from its equilibrium position describes the amplitude of the wave.
2. Electric current can be defined as the rate of flow of charge in a conductor.
3. Gamma radiation can pass through both electric and magnetic fields without any deflection because they have no charge.
4. During the process of nuclear fusion in the sun, isotopes of hydrogen combine to form helium atoms and release a huge amount of energy and a neutron.

Significant Figures

The number 0.000345000 has 6 significant figures.