P4 Flashcards
What is a wave
- oscilliation/vibration
- transfers energy from one place to another
What is a transverse wave
Where the oscilliation is perpendicular to the direction of energy transfer
What is wave motion
the transfer of energy from one point to another
What does Wavespeed mean
the total distance covered by the wave in a given amount of time.
What does frequency mean
how many complete waves go past a certain point in one second
What does wavelength mean
Distance between two successive peaks or troughs (highest or bottom) of a wave
What does amplitude mean
The distance from the equilibrium to the peak or trough.
Formula for wave speed
wave length multiplied by the frequency makes the wave speed
Formula for frequency
Wave speed divided by wave length makes the frequency
Formula for wave length
Wave speed divided by frequency makes the wave length
Units for frequency
is Hz
What is a longitudal wave
The oscialliation/vibration is parallel to the energy transder
Examples of a longitudal wave
Sound
What is a compressioin and where do you find it
Where particles are closest together in a longitudal wave
Examples of a transverse wave
Light, water vaes, string vibrations
What is a rarefraction and where do you find it
Where particles are most spread out in a longitudal wave
What is another way to find frequency other than using the wave formula
Using the inverse of time taken (1/t)
What is another way to find speed other than using the wave formula
Distance over time
Units of wave speed
m/s
Units of frequency
Hz
How do we see light
when light reflects of the object and into our eyes
Units of wavelength
m
What is the law of reflection
the angle of incidence and angle of reflection are the same
Common errors in light based experiments
varying intensity of lights, human error, and others.
How is a image formed in a plane mirror
Light rays: Light rays from an object travel towards the mirror.
Incidence: The light rays hit the mirror at a specific angle, called the angle of incidence.
Reflection: The mirror reflects the light rays, and they bounce back at the same angle as the angle of incidence
Virtual image: The reflected light rays appear to come from a point behind the mirror, creating a virtual image.
The virtual image is formed at a distance equal to the distance between the object and the mirror.
Properties of optical image in plane mirror
Virtual, samze size and distance from the real object, and laterally inverted.
What is refraction
a change in direction of light due to the slowing down of the speed of the ray as it passes from one medium to another.
When does light bend towards the normal
when it enters a denser medium that it was previous travelling through as it slows down.
When does light bend away from the normal
when it enters less denser medium thn it was previously traveling through causing it speed up.
Method to find refractive index of object using angle of incidence and refraction
sin(angle of incidence)/sin(angle of refraction)
Method to find refractive index without using angle of incidence and refraction
Speed of light in a vaccum divided by speed of light in the medium
What is the speed of light
3*10^8
What happens when angle of incidence is less than critical angle
It will speed up and bend away from the normal
What happens when angle of incidence is equal to the critical
It will not internally reflect but come out at perpindicular to the normal
What happens when angle of incidence is larger than the critical angle
Total Internal Reflection meaning it reflects off that boundary
Why is it impossible for total internal refelction to occur when travelling through a denser material
the angle of refraction is always lesser than the angle of incidence
What does critical angle mean
The angle which the maximum refraction (90 degrees) occurs. The ray travelling along the boundary
How does optical fibres work
total internal reflection,they rely on all angle of incidences being larger than the critical angle so the light doesn’t come out the side
Uses of fibre optics
Communications, medecine such as endoscopes, and the internet
What does a thin converging lens act on a beam of light
It will make all parralell rays of the line refract and come together at a certain point called the principal focus.
What is the principal focus
the point where all incident rays meet after refraction
What is a focal length
the distance between the centre of lens and principal focus
What is a converging lens also called
a convex lens
What is the result of using a thin or thick converging lens
a thicker lens will have a shorter focal length as they refract the parralell rays more
What happens when a ray passes a converging lens not through the ceneter of the lens but parralel to the principal axis
it is refracted so it passes through the principal focus
What image is created when the object is placed within the focal length
it produces a magnified image that is virtual, same side of the object, and upright
What is a real image
something that can be projected on a screen
what is a virtual image
something that can’t be cast on a screen
What is the speed of light
3*10^8
how does our eyes recieve light waves
in the retina the light energy is converted to electrical energy. Different wavelengths are converted to different colors. Red has the longest wavelength and violet has the shortest
3 properties of electromagnetic waves
don’t require a medium to travel
All transfer energy via vibrations of electric and magnetic fields.
all travel at the speed of life roughly
Order of electromagnetic waves from shortest to longest wavelength
Gamma, x-ray, ultraviolet, visible, infrared, microwave, radio
Properties and uses of radio waves
Properties:
Long wavelength
Low frequency
Uses:
radio, television, communications
Properties and uses of microwaves
Properties
High frequency
Penetrate and heat materials
Uses
Cooking and heating food
satellite television and telephones (
Properties uses and dangers of infrared rays
Properties
Heat transfer
Uses
electrical appliances, remote controllers for televisions and intruder alarms
Dangers
Heat damage and burns
Properties uses and dangers of visible light
Properites:
Visible to the human eye
Dangers:
UV radiation exposure
Properties, uses, and dangers of ultraviolet light
Properties
High frequency
Low wavelength
Uses
Disinfection and sterilization
Water purification
Dangers
Skin cancer and premature aging
Properties, uses, and dangers of x-rays
Properities
penetrates solid objects
uses
Medical imaging (diagnosis, cancer treatment)
Security screening (airport scanners)
Dangers
Cancer risk and genetic damage
Radiation burns and tissue damage
Properties, uses, and dangers of gamma rays
Properties
Highest energy and penetration
Uses
Cancer treatment
Dangers
High-energy radiation exposure
Cancer risk and genetic damage
What is sound
a longtidual wave caused by vibrations
What is a rarefraction
the part of a longitudal wave where particles are the most spread
what is a compression
part of a longitudal wave where particles are closest together
What is the normal hearing range of humans
20 Hz to 20kHz
What do we call sound too low to hear
infrared sound
What do we call sound too high to hear
ultrasound
What is a experiment to find the speed of sound in air
2 speakers at a distance known. Have a noise made and a timer that starts. Once the noise is reached by second speaker stop timer and divide the distance known and the time taken for sound to cross to the other speaker
What is required for sound to move
A medium
How fast does sound move in each state of matter
Solid>Liquid>Gas
Why does sound move fastest in solids
In a solid the molecules/atoms are very close together, in fixed positions and can pass on the vibrations very easily to their neighbour.
What is a echo
when sound hits a reflecting surface and bounces back from it.
What do sound waves look like in. a oscollioscope
a transerverse wave. A low sound will have a low frequency and a high sound will have a higher frequency. A loud sound will have a high amplitude and vice verca
What is the speed of sound in air
330m
What is a wavefront
a line joining neighbouring points which are in phase
What can cause a circular wave front
a dipper in a water
what can cause a plane wave front
a vibrating bar in water
How does a wave travel have anything to do with wave fronts
always 90 degrees to the wave front
Doeswater travel faster in higher or low desnity
low density or shallow
What happens to waves when entering shallow water from deeper water
it’s wavelengtha and speed decrease while their frequency stays the same
What is diffraction
the spreading out of waves round obstacles and through gaps
How does gap size affect diffraction
The smaller the gap is in comparison of the wave fronts the more spread and sector it looks. Or themore wavelength is closer to the gap the less affected it is by diffraction
