GENPHY II

• A vibrating charge generates a time-varying magnetic field that induces a time-varying electric field.
• electromagnetic (EM) wave is composed of sinusoidal time-varying magnetic and electric fields that are at right angles with each other
• electromagnetic (EM) wave are traveling at a speed (c) of 2.99 ✕ 108 m/s in free space.
• Frequency - number of a wave’s vibrations or

  oscillations per unit time.
• Wavelength - distance between two crests or two troughs.
• Amplitude - vertical distance between the central axis of a wave and the tip of a crest.
• wavelength and frequency are inversely proportional
• any increase in frequency results in a subsequent decrease in wavelength
• Infrared Radiation - commonly emitted as thermal energy. Used in heat-sensitive thermal imaging, night-vision cameras, detecting heat patterns, and security cameras.
• A luminous object releases or emits light in different directions.
• an illuminated object reflects light in various directions.
• Incident ray – light which falls on the mirror/ polished surface
• Reflected ray – ray of light which goes back in the same medium after striking the surface
• Normal – the perpendicular drawn to the reflecting surface is called normal at that point.
• Wave-particle duality of light says that light possesses both wave and particle properties, even though we cannot observe both at the same time.
• The Scottish scientist James Clerk Maxwell (1831–1979) was responsible for the theoretical prediction of electromagnetic waves, which unified all electrical and magnetic phenomena into a single beautiful theory.
• Electromagnetic radiations are composed of electromagnetic waves that are produced when an electric field comes in contact with the magnetic field.
• Electromagnetic waves are the composition of oscillating electric and magnetic fields.
• electromagnetic spectrum is a range of frequencies, wavelengths and photon energies covering frequencies from below 1 hertz to above 1025 Hz.
• EM waves are produced by electric charges that are oscillating, and hence are undergoing acceleration
• accelerating electric charges give rise to electromagnetic waves
• light only visible to the human eye because of the form and sensitivity of our eyes ' photoreceptor cells, the rods and cones in the retina, as well as a certain range of the electromagnetic spectrum
• the wavelengths vary approximately from 400 nm to 700 nm
• A photon is a fundamental particle that represents a quantum of electromagnetic radiation.
• A photon is the basic unit of light and other forms of electromagnetic radiation. They are massless and travel at the speed of light in a vacuum
• The incident ray, the reflected ray, and the normal all lie in a similar plane called the plane of incidence.
• The angle of incidence and the angle of reflection are equal regardless of the wavelength or pair of materials
• The plane of incidence is at right angles to the plane of the surface of the boundary between the two objects.
• Refraction is the bending of light (or other waves) as it passes from one transparent substance into another with a different refractive index.
• Refractive Index - ratio of the speed of light in free space to that of its speed in a given medium.
• Inert tendency of a material’s molecules determines a material’s refractive index to keep the absorbed energy of an EM wave in the form of oscillating electrons before releasing it back as a new disturbance.
• Snell’s law (or the Law of Refraction) describes the relationship between the angle of incidence θa and the angle of refraction θb as light passes through two different media.
• Ratio of the sines of the angle of incidence θa and angle of refraction θa

  (considering both are measured relative to the normal to the surface) is equivalent to the inverse ratio of the two indices of refraction
• Total Internal Reflection - The angle of incidence is greater than the critical angle/refraction.
• The incident angle that produces angle of refraction = to

  90° is called the critical angle.
• Dispersion refers to the scattering of white visible light into a full spectrum of wavelengths.
• The refractive index and the wavelength are inversely proportional.
• An optical prism is defined as a transparent refractive material with precise angles and plane faces.
• The Angle of Deviation - angle formed between (1) the light’s incident ray entering the face of the prism adjacent to the light source

  and (2) the refracted ray that comes out of the prism’s second face.
• The angle of incidence of a light ray that strikes the first face of a prism determines the angle of deviation.