Waves Flashcards
What types of energy is there? (7)
Kinetic, Potential, Heat, Light, Sound, Electrical, Radio waves
What are waves?
Waves are vibrations that transfer energy from place to place without matter (solid, liquid or gas) being transferred. The medium may vibrate though.
What’s a medium?
Some waves must travel through a substance. The substance is known as the medium and it can be solid, liquid or gas. Sound waves and seismic waves are like this. They must travel through a medium, and it is the medium that vibrates as the waves travel through.
What kind of waves don’t NEED to travel through a medium, but can if they have to? (4)
Visible light, infrared rays, microwaves and other types of electromagnetic radiation. Electrical and magnetic fields vibrate as the waves travel.
Whats a wavelength?
From 1 crest to another, or from one compression to another.
What is the amplitude?
The distance between the crest or trough, to the equilibrium.
What’s the frequency of a wave?
The frequency of a wave is the number of waves produced by (or pass a point) a source each second.
What can humans see?
Visible light, which is a very small part of the EM spectrum.
What does EM stand for?
Electromagnetic Waves.
How do people see?
People see when light waves from a source reflect off an object and their eyes from all directions.
List the types of waves from smallest to largest energy.
Radio waves (AM, FM, TV, Radar)
Microwaves
Infared
Light
Ultraviolet
X-Rays
Gamma Rays
List the types of waves from smallest to largest wavelengths.
Gamma Rays
X-Rays
Ultraviolet
Light
Infared
Microwaves
Radio waves (Radar, TV, FM, AM)
How are the colours of visible light made?
Electromagnetic energy of various frequencies and wavelength. Red has the largest wavelength and violet, the smallest.
What is white light made up of?
All the wavelengths of visible light. When white light is refracted, it splits into all its component colours
How is a rainbow produced?
A raindrop acts like a prism causing white light to refract, and the colours all bend at different angles.
What colours can only be seen when a certain combination of wavelengths is present?
Pink and Brown
What is the colour of an object determined by?
The wavelengths of light it reflects. So, if an object reflects one wavelength, it absorbs all the other wavelengths of visible light. An objects that absorbs all light is black and an objects that reflects all light is white.
What are the 2 types of lenses?
Convex (curve outwards aka converging) and concave (curve inwards aka disverging).
What is the principle focus?
Where all the rays meet in. In a convex lens, the principle focus is after the lense and in a concave, it’s before.
What’s the focal length?
The distance from the centre (plane)
of the lens to the principle focus.
How does the shape of a lense effect the focal length?
The greater the lens curves, the more it bends light and hence the shorter the focal length. A ray passing through the centre of either type of lens is unaffected (principle axis).
What’s a real image?
If the object is at a further than the focal length, a real image is formed.
What’s a virtual image?
If the object is at a distance less than the focal length, a virtual image is formed. This image can’t be projected. Concave lenses produce only virtual images.
What does inverted mean?
Upside down in comparison to the original object.
What does diminished mean?
Smaller than the original object.
When are concave mirrors needed?
To enlarge and object.
When are convex mirrors needed?
To produce a smaller image. Convex mirrors are useful when a wide view is needed. They are used in shops for security and in some car rear-vision mirrors.
Which part of the eye creates the most refraction?
Cornea (outermost layer in the front).
What’s a lens?
A lens is an optical device that focuses or disperses light beams using refraction.
What’s the maginification calculation?
Image height
_______________
Object height
What’s the refraction index?
The measure of bending of a light ray when passing from one medium to another.
Are sound or light waves faster?
Light waves are faster.
What does the wave amplitude determine in a sound and light wave?
How loud a sound is, and how bright a light is.
What is λ?
Symbol for wavelength.
What’s f?
Frequency of a wave, measured in Hertz (Hz).
What is the relationship between wavelength and frequency?
The faster the frequency, the shorter the wavelength, although the amplitude stays the same.
What’s the formula for velocity?
v = λ x f
v = velocity (m/s)
λ= wavelength (m)
f = frequency (Hz)
or λ
–
t (period)
What’s period?
The number of seconds it takes for one wave to pass through a point.
Example of radio wave and microwave and UV rays.
Communication, and GPS, suntanning respectively.
Are colours real?
Colour is the way your brain interprets the information from the eye regarding the frequencies of light.
What’s absorbtion?
The energy of the wave can be absorbed by a substance. It causes some particles in the substance to vibrate, becoming heat energy. Even transparent substances absorb some light.
What’s shiny and dull?
Surfaces that are very smooth at the microscopic level cause beams of light to bounce off uniformly. This appears “shiny”. Surfaces that are rough cause light waves to bounce off in all directions. Since only part of the light comes to your eye, the surface dull. Mirrors are so smooth that light reflects almost perfectly.
Why does refraction happen?
As light rays travel from one medium to the next, they change direction, refracting.
What does light bend towards?
When refracting, the incident light ray bends towards the normal.
Frequency Formula
f = 1/T
Period Formula
T = 1/f
Wave Speed Formula
Frequency x Wavelength
