Physics P1 Flashcards
Heliocentric model
Sun in the centre with everything orbiting it with the moon orbiting earth
Geocentric model
Earth is in the centre and everything orbits it, moving in its own little circle
Interface
Boundary between two materials
An image from a converging lense
Upside down, a real image
Real image
An image where the rays of light actually meet at the point where the image is seen
Virtual image
The rays of light appear to come from an image but actually don’t. A virtual image cannot be shown on a screen
Image from a reflecting telescope
Right way round, sharper, virtual image
Frequency
The number of waves passing a point each second
Measured in hertz (Hz)
Wavelength
The distance from a point on one wave from the same point on the next wave. Measured in metres
Amplitude
The maximum distance of a point on the wave from its rest position. Measured in metres.
Wave speed equation
Wave speed (metres/second) =
Distance (metres)
————- = —————-
Time (seconds)
Wave speed
frequency x wavelength
Hz x m
Electromagnetic spectrum
Radio waves, microwaves, infrared, visible light, UV, X-rays, gamma rays
Shortest wavelength, highest frequency, most dangerous
Uses of electromagnetic radiation
UV- Shine it on banknotes
Radio waves- broadcast and communication
Infrared- CCTV camera , remotes, toasters,optical fibres
Microwaves- mobile phone signals
Gamma rays- detect and kill cancer, sterilise medical equipment
Ionising radiation
Radiation that removes electrons from atoms to form ions, these can mutate and cause cancer
Parts of the electromagnetic spectrum telescopes can detect
Visible light, X-rays, ultraviolet, radio waves
Life cycle of star
Cloud of gas (nebula), protostar, average star,
- red giant, shell of gas, white dwarf, black dwarf.
- red supergiant, supernova, neutron star or black hole
Big Bang theory
The whole universe and everything in it started out as a tiny piece of matter around 13.5 billion years ago. The universe expanded and is still expanding. Nothing is being created, and everything is moving away from each other.
Steady state theory
The universe has always existed and is expanding, new matter is being created to fill the spaces.
Red shift
When the wavelengths from far off stars and galaxies is longer than expected
Infrasound
Sound with frequencies below 20 Hz
Elephants and whales use it to communicate
Can be used to detect earthquakes an meteors
Ultrasound
Sound with a frequency above 20 000 Hz
Dolphins use it to communicate
Bats use it to detect their surroundings
Boats use it to detect how deep the water is
Can be used to make images of things inside the body
Seismic waves
Movements inside the earth, such as earthquakes,which cause waves to be transmitted through the earth.
Seismometers
Instruments that detect seismic waves