Chapter 6 - Waves Flashcards
What is the equation for wavespeed?
wavespeed = wavelength x frequency
What is the frequency of a wave?
Number of waves per second (measured in Hertz)
What is wavelength?
The distance between the same point on two consecutive waves (measured in metres)
What is time period?
Time taken for one complete wave
What is the equation involving time period and frequency?
Frequency = 1 / time period
OR
Time period = 1 / frequency
What are electromagnetic waves?
- Transverse
- Travel at the speed of light (300 000 000 m/s)
What waves are on the electromagnetic spectrum (in order smallest to largest frequency / longest to shortest wavelength)
- Radiowaves
- Microwaves
- Infra-red
- Visible light
- Ultra-violet (UV)
- X-rays
- Gamma rays
What is true about the image produced by the reflection of an object in a plane mirror?
- Image is the same size as the object
- Distance from the mirror is the same
- Image is laterally inverted (flipped sideways)
What is infrared radiation?
Heat energy waves. They will travel out from a hot source in all directions and can travel through a vacuum. All objects absorb and emit infrared radiation.
What surfaces are good absorbers?
Dull and black surfaces = the best absorbers
What surfaces are the best reflectors?
Shiny and white surfaces = the best reflectors
What is refraction?
The change of direction of a light ray when it passes a across a boundary into a substance of a different density.
What happens during refraction?
- When light enters a dense material, it changes speed and bends towards the normal
- When light enters a less dense material, it changes speed and bends away from the normal
What is sound?
- made up of longitudinal waves
- travels fastest through solids
- can’t travel through vacuums
Sound is described by its amplitude and frequency. What do amplitude and frequency determine?
Large amplitude = loud sound
Small amplitude = quiet sound
Higher freq = higher pitch
Lower freq = lower pitch
What are the units for volume and pitch?
Volume = decibels (dB)
Pitch - Hertz (Hz)
What are echos?
Reflections of sound
What is the human hearing range?
20 Hz - 20,000 Hz
What are ultrasound waves?
Sound waves with a frequency above 20,000 Hz
What are the uses of ultrasound?
- SONAR
- Ultrasound imaging
- Kidney stone removal
- Cleaning delicate objects
What are the primary colours of light?
- Blue
- Red
- Green
What are the secondary colours of light?
- Magenta
- Cyan
- Yellow
What is white light made up of?
Red, blue and green light waves
What is the colour black?
The absence of light/colour
What way do light rays bend when they travel at convex lens in a straight line?
Bend twice in same direction inwards. Point where they cross is called the focus point
What way do light rays bend when they travel at concave lens in a straight line?
Bend twice in same direction outwards.
What rays form a real image?
Real rays
What rays form a virtual image?
Virtual rays
What is a black body
Something that is perfect at absorbing and emitting all
radiation
What are the two types of seismic waves?
P-waves and S-waves
Properties of P-waves
- longitudinal
- faster
- travel through solids and liquids
Properties of S-waves
- transverse
- slower
- solids only
What are seismic waves produced by?
Earthquakes
