Waves Flashcards
What are all sounds cause by?
A vibrating object
What is the amplitude of a wave?
The amplitude of a sound is how loud it is. The amplitude is the distance from the line of 0 disturbance to the top of the wave
What happens to a wave trace when the amplitude is increased?
The waves will get taller and sound louder
What happens to a wave trace when the amplitude is decreased?
The waves will get smaller and will sound quieter
What is the frequency of a wave?
The frequency of a wave is its pitch. A high note = high pitch and a low note = low pitch
What happens to a wave trace when the frequency is increased?
More waves will appear in the period of time and the sound will be higher pitched
What happens to a wave trace when the frequency is decreased?
Less waves will appear in the period of time and the sound will be lower pitched
What is the frequency of human hearing?
20Hz-20,000Hz
When a sound is below 20Hz or above 20,000Hz what happens?
It becomes inaudible to humans
What is refraction?
Refraction is the change of speed which occurs when light travels from one optical medium to another
What happens to light when it undergoes refraction?
When light undergoes refraction it need not change direction, it will change speed and bend towards the normal
What is the normal?
The normal is an imaginary line perpendicular to the surface at which light enters the Perspex
What is the angle of refraction?
The angle of refraction is measured between the refracted ray and the normal
What is the angle of incidence?
The angle of incidence is measure between the incident ray and the normal
What happens when light passes through the Perspex?
The light will pass through in 1 beam in an undisturbed line. When the incident ray passes into 90° to the normal it does not change path
Describe how a converging lens focuses light
A converging lens bends the light into one focal point and back out to form a clear image
Describe how a diverging lens focuses light
A diverging lens bends light away causing you to look for a virtual focal point. The virtual focal point is where the rays have come from so the focal length is negative
How does an image appear when produced by a converging lens?
It will appear diminished, horizontally flipped and vertically flipped
What is the equation for measuring the optical power of a lens?
Optical Power= 1/Focal length
Or…
P=1/F
How do you measure the focal length of a converging lens?
F=1/P
Thicker lenses have a greater what, than a thinner lens?
Lenses with greater curvature have a higher optical power
What is the relationship between optical power and focal length?
P=1/F
What is the optical power measured in?
Diopters (D)
What is the focal length measured in?
Meters (m)
What is the function of the cornea?
Transparent outer lens which does most of the eyes refraction
What is the function of the lens?
Focuses light onto the retina. Changes thickness to vary the amount of refraction
What is the function of the pupil?
An aperture (hike) which allows light in, it changes size according to how bright it is
What is the function of the retina?
The light sensitive coating at the back of your eye. Retina cells change light energy into electrical signals sent to the brain
What is the function of the optic nerve?
Takes electrical signals from the retina to the brain
What effect does light have on the pupil of the eye?
In brighter conditions the pupil shrinks as the eye can only take in so much light at a time therefore when a lot of light is present it can’t take it in therefore shrinks. When the light is dim the pupil grows so it can take in as much light as possible
What causes the blind spot in the eye and what effect does it have on your vision?
There is a point in the retina at which the optic nerve is connected cannot detect light because there are no light sensitive cells this is your blind spot. Light from an object landing on your blind spot cannot be seen
What happens to the image formed by a converging lens when the object is brought closer?
When the object is moved closer the image gets bigger
How does the eye accommodate to distant and near objects?
If the object is near to the eye the lens will thicken and if the object is far away the lens will become thinner and relax
What is meant by accommodation of the eye?
The eye accommodates it’s lens thickness based on how near or far an object is
Describe the nature of rays of light coming from a distant object
When rays of light come from a distant object they will come together in parallel to form a focal point and then back out
Describe that nature of rays of light coming from a near object
The rays of light coming from a near object will
