Physics- Year 9 Flashcards
Wave
Transmitter of energy without the movement of particles from place to place. The vibration of particles or energy fields is involved
Transverse wave
Waves involving the vibrations of particles perpendicular to the direction of energy transfer
Travel at a right angle to the direction of energy transfer
Compression wave
Wave involving the vibrations of particles on the same direction as energy transfer
Particles move backwards and forwards in the same direction as energy transfer
Sound is a compression wave
Compression vs rarefaction
Compression = pushed together Rarefactions= pushed apart
Frequency
Number of vibrations in one second or the number of wavelengths padding in one second
Measured in hertz (Hz)
Pitch
Highness or lowness of a sound. The pitch you hear depends on the frequency of the vibrating air
High frequency = high pitch
Wavelength
Distance between two neighbouring crest or troughs of a wave. This is the distance between two vibrations particles in step.
Amplitude
Maximum distance that a particle moves away from its undisturbed position
Ultrasound
Sound with frequencies too high for humans to hear. Used in medicine to produce images of babies, gallstones, circulation problems and cancer
Sonar
Use of reflected sound waves to locate objects underwater. Used on ships, high frequency sound is transmitted from the ship. They calculate underwater objects by time taken for the echo to return= echolocation
Speed of sound
- Speed is greater in liquids and solids cause particles are closer together
- Speed of sound in air is greater at higher temps
- Speed of sound in particular medium depends on how close the particles are to each other and how easy they are to push together
Electromagnetic spectrum
Complete range of wavelengths of energy radiated as electric and magnetic fields
Radio waves
Include the low energy waves that are used in radio and television. Also includes radar and microwaves. Has a much lower frequency and longer wavelength then visible light
Infrared Radiation
Invisible radiation emitted by all warm objects. Feel it as heat. Invisible to human eye
Visible light
Very small part of the electromagnetic spectrum which our eyes are sensitive. Necessary for the sense of sight
Ultraviolet radiation
Invisible radiation similar to light but a slightly higher frequency. Causes sunburn
X-rays
High-energy electromagnetic waves that can be transmitted through solids and provides informations about their structure
Gamma rays
High energy electromagnetic radiation produced during nuclear reactions. No mass and travels at speed of light
Order of the electromagnetic spectrum
Gamma rays X-rays Ultra violet Infrared Radio waves
Difference between electromagnetic waves and sound waves
Electromagnetic are transverse waves and sound are longitudinal
Electromagnetic can travel through a vacuum and sound can’t
Electromagnetic travels at 300 000 000m/s and sound is lower than 330-350m/s
Rays
Light that are used to show path of a light
Beams
You can only see multiple rays together
Transparent
Describes a substance that allows most light to pass through it objects can be seen clearly through transparent substances
Translucent
Allowing light to pass through imperfectly eg, frosted glass