Waves

• The amplitude of a wave is the maximum displacement from its undisturbed position.
• The wavelength of a wave is the distance between two consecutive points on the wave.
• Frequency of a wave is the number of complete waves passing a point per second.
• Frequency is measured in Hertz (Hz)
• In Transverse waves, the oscillations are perpendicular to the energy transfer.
• In Longitudinal waves, the oscillations are parallel to the direction of energy transfer.
• Wave Speed in measured in m/s
• An oscilloscope is used to measure the speed of sound
• All waves can be transmitted, absorbed or reflected
• Angle of incidence = Angle of reflection
• Reflection can be specular or diffuse
• Specular Reflection occurs when light hits an object at a smooth surface
• Diffuse Reflection occurs when light hits an object with a rough surface
• The angle between the incident ray and normal line is called the angle of incidence (i)
• The angle between the refracted ray and normal line is called the angle of refraction (r)
• All EM Waves are transverse
• Electromagnetic Waves can travel through a vacuum
• EM waves move at the speed of light
• The Speed of Light= 3x10^8 m/s
• The Speed of Sound= 330m/s
• Sound travels faster through solids than liquids, which travel faster than gases.
• Red Men In Very Unusual X-Ray Goggles = EM Spectrum
• Radiowaves, Microwaves, Infrared, Visable Light, Ultraviolet, X-rays, Gamma rays
• Radiowaves are mainly used for communication
• Microwaves are used to heat food
• Infrared can be used to increase or monitor temperatures
• Fibre Optic Cables use Visable Light to transmit Data
• Visible Light Spectrum: Red, Orange, Yellow, Green, Blue, Indigo, Violet
• Ultraviolet radiation is used to sterilise food and drink
• X-Rays and Gamma Rays are used in medicine
• Radiation Dose is measured in Sieverts (Sv)
• Radiation risks are different depending on what part of the body it affects
• A convex lens causes light to converge (becoming closer together)
• A concave lens curves inwards and diverges light
• Distance from the centre of the lens to the centre of the principal focus is called the focal length
• Lenses can produce real and virtual images
• To describe an image properly you need to say whether it is inverted or upright, how big it is compared to the objects and whether the image is real or virtual
• Concave lenses always create virtual images
• Magnifying Glasses use concave lenses to magnify objects.
• Magnification= image height / object height