P5 Waves Flashcards
Waves are…
The transfer of energy / information
In a transverse wave the oscillations are…
Perpendicular to the direction of energy transfer
Wavelength is:
The length of one wave (peak to peak)
Measured in metres
Amplitude is:
Maximum displacement of oscillation
(Middle to either top or bottom)
Speed:
Distance wave travels in a given time
Oscillate means…
To move back and forwards, vibrate
Name two examples of transverse waves
Light
Water
In a longitudinal wave oscillations are…
Parallel to the direction of the wave
Name two examples of longitudinal waves
Sound waves
Earthquakes
Frequency is:
The number of oscillations per second
Period is:
The time is takes for one oscillation
T = 1/f
What do the letters stand for?
Period = 1 / frequency
The speed of sound in air is…
330m/s
A sonic boom is…
When an object eg an aeroplane goes faster than the speed of sound. The sound waves catch up with earlier sound waves producing a shockwave
How do we hear sounds?
Vibrations produce a sound wave wich travels through the medium (eg air) to our ears
Humans can hear frequencies from…
20Hz to 20 kHz
What is resonance?
Every object has a natural frequency. When it vibrates at this frequency, it vibrates with a larger amplitude than any other frequency. This large vibration is called resonance
Any sound above ___ can begin to damage your hearing
85dB
What is the law of reflection?
The angle of incidence is equal to the angle of reflection
Images in mirrors appear…
Upright
The same size
Virtual
Laterally inverted
Equidistant from the mirror
What does specular mean?
The light is all reflected at the same angle
What does diffuse mean?
The light is all reflected at different angles
Convex lenses are…
Thicker in the middle than at the edges
Convex lenses cause light rays to…
Converge at the focal point
Concave lenses are…
Thinner in the middle than at the edges
Concave lenses cause light rays to…
Diverge from each other
The primary colours of light are…
Red
Green
Blue
Filters ____ all colours except the ones they are designed to ____
Absorb
Let through
What is the equation for wave speed?
Wave speed = frequency x wavelength
What is the equation for frequency?
Frequency = number of oscillations / time taken
What is the EM spectrum from low to high frequency?
Radio
Microwave
Infrared
Visible
Ultraviolet
X-ray
Gamma
Gamma rays carry the ___ energy of all electromagnetic waves
Most
Gamma rays are used for…
Medical imaging and therapy
Astronomy
Sterilisation
Food preservation
Why are gamma rays dangerous?
They are extremely penetrating and damaging to living tissues + cells
X-rays carry the ___ energy of electromagnetic waves
Second most
Why are x-rays dangerous?
Highly ionising - can damage cells
What are x-rays used for?
Low energy x-rays are used for medical and industrial imaging
High energy x-rays used to treat cancer
Also used for security eg in airports
What are the risks of ultraviolet light
Can cause skin burns, cancer and cataracts
What is ultraviolet used for
Medical and forensic photography
Air purification, disinfection and medical therapy
Detecting fake bank notes
