Understanding Electromagnetic Waves

• Electromagnetic waves are disturbances transferring energy through space.
• Unlike mechanical waves (sound, water), electromagnetic waves don't need a medium.
• Electromagnetic waves arise from accelerating charged particles.

Properties of Electromagnetic Waves

• Both electric and magnetic field components oscillate perpendicularly to each other and to the propagation direction.
• They travel at the speed of light in a vacuum (c ≈ 3.00 x 108 m/s).
• Electromagnetic waves exhibit wave-like behavior, including refraction, diffraction, and interference.
• They exhibit particle-like behavior like the photoelectric effect and Compton scattering.
• The waves carry energy that interacts with matter.
• Energy is related to a wave's frequency and amplitude.

Electromagnetic Spectrum

• It's the classification of electromagnetic waves by frequency (or wavelength).
• From lowest to highest frequency: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
• Radio waves are used for communication (radio, TV) and have long wavelengths.
• Microwaves are used for cooking and communication, with shorter wavelengths than radio waves.
• Infrared is felt as heat and is used in remote controls and thermal imaging.
• Visible light is the portion we can see; different wavelengths correspond to different colors.
• Ultraviolet can cause sunburns and is used in sterilization.
• X-rays are used in medical imaging and can penetrate soft tissues.
• Gamma rays are emitted by radioactive materials and possess very high energy.

Wave equation

• c = λf, where c is the speed of light, λ is the wavelength, and f is the frequency.
• Energy of a photon: E = hf, where E represents energy, h is Planck's constant (6.626 x 10-34 J·s), and f is frequency.
• Higher frequency electromagnetic waves have shorter wavelengths and carry more energy per photon.

Reflection of Light

• Light reflection is the change in direction of a light ray bouncing off a surface.
• Reflection enables us to see objects that don't produce their own light.

Laws of Reflection

• The angle of incidence (θi) equals the angle of reflection (θr).
• Both angles are measured relative to the normal, perpendicular to the surface at the point of incidence.
• The incident ray, reflected ray, and normal lie in the same plane.

Types of Reflection

• Specular reflection occurs on smooth surfaces (mirrors); reflected rays are parallel, producing a clear image.
• Diffuse reflection occurs on rough surfaces (paper); reflected rays scatter in different directions, with no clear image produced.

Plane Mirrors

• These are flat, reflective surfaces producing virtual images.
• Virtual images occur when light rays don't converge at the image location; the image appears behind the mirror.
• The image appears the same size as the object.

Image Characteristics of Plane Mirrors

• Images are upright (not inverted).
• Images are virtual (cannot be projected onto a screen).
• Images are located the same distance behind the mirror as the object is in front.
• Images are laterally inverted (left and right are reversed).

Applications of Plane Mirrors

• Used in dressing mirrors for reflection viewing.
• Used in periscopes to see over or around obstacles.
• Employed in security systems.
• Integrated into optical instruments.

Image Formation

• Light rays from the object reflect off the mirror surface.
• Our brains trace these reflected rays back to perceive an image behind the mirror.
• The image is virtual because the rays only appear to come from behind the mirror and don't actually converge there.

Multiple Reflections

• Multiple reflections occur when two or more mirrors are arranged at an angle.
• The number of images depends on the angle between the mirrors.
• The equation n = (360/θ) - 1 determines the number of images (n), where θ is the angle between the mirrors.

Parallax

• It is the apparent shift in an object's position when viewed from different locations.
• Parallax can determine the distance to an object.
• Parallax can be observed when viewing a plane mirror image by moving your head side to side.

Color Reflection

• An object's color depends on the wavelengths of light it reflects.
• A red object reflects red light and absorbs other colors.
• A white object reflects all colors of light.
• A black object absorbs all colors of light.