Forensics Physics Flashcards
What is a wave?
A wave of is an oscillation in a medium.
What is an oscillation?
It is a vibration or periodic movement.
What is a medium?
The medium is the thing that a wave travels through. E.g.air
What is displacement?
The distance from equilibrium (M)
What is amplitude?
Maximum displacement (m)
What is wavelength?
The distance travelled in one oscillation. (M)
What is frequency?
How many oscillations there are per second. (Hz)
What is period?
The time taken for one oscillation to occur. (S)
What is the equation that links frequency and period?
F= 1/T
T=1/F
What is the equation that links speed, distance and time?
Speed= distance/time
What is the equation that link wave speed, wavelength and frequency?
Wave speed= wavelength/ frequency
How fast does light travel through a vacuum?
3.00x10^8 m/s
What is a radio wave produced by and what is it used for?
Electronic oscillators coupled to broadcast antennas . It is used for radio and TV broadcasting,mobile phones, plasma heating for fusion reactors and industrial ovens. They have the lowest frequency and the longest wavelength.
What are microwaves produced by and what are they used for?
They are produced by klystron or magnetron tubes or solid state diodes. They are used in domestic ovens, satellite and terrestrial communication links.
What are microwaves produced by and what are they used for?
They are produced by light emitting diodes, lasers or thermal emission. They are used for night vision cameras, optical fibre communications, movement detectors, remote controls and spectroscopy.
What is visible light produced by and what is it used for?
It is produced by the emission of outer electron transitions. It is used for illumination, imaging,signalling, photosynthesis in plants and spectroscopy.
What is ultra violet produced by and what is it used for?
It is produced by emission by outer electrons transition. It is used. For insect vision and tanning.
What are x-rays produced by and what are they used for?
They are produced by accelerating electrons through a potential difference and they are use for medical imaging.
What is a gamma ray produced by and what is it used for?
It is produced by nuclear reactions and particle decay. It is used for medical treatments. It is the highest frequency and shortest wavelength.
What is a transverse wave? Give and example
A transverse wave is a wave where the particle oscillate perpendicular to the direction of the wave travel and energy transfer. An example is electromagnetic waves.
What is a longitudinal wave? Give and example.
A longitudinal wave is when the particles oscillate parallel to the direction of energy transfer and the direction a wave travel. An example is sound waves.
What are the uses of polarisation?
- electromagnetic radiation
-plane, monochromatic wave
-electric and magnetic fields are orthogonal and transverse to the direction of propagation.
What happens is something is polarised, polarised in he vertical direction and unpolarised?
Polarised: the electric field always points in the same direction.
Polarised in the vertical direction: the electric field points in the vertical direction.
Unpolarised: superposition of many beams approximately parallel but each with random polarisation.
What is a photon?
A light particle which has no mass and it moves at the speed of light. It behaves as a wave and a particle. It has no charge.
