Paper 4 Higher Flashcards
What is the frequency of wave?
The number of complete cycles of a wave passing a certain point per second (Hz)
What do waves transfer?
Energy, but not matter. If you drop a twig into calm water, the rippled form and move across the surface, without carrying the water or the twig away with them.
How could you generate water waves at a fixed frequency in a ripple tank?
- use a dipper attached to a signal generator
- the signal generator moves up and down at a constant frequency
- which creates waves with the same frequency
How could you find the frequency of a wave in a ripple tank using a cork and a stopwatch?
- float the cork on the water
- start the stopwatch when the cork is at the top of a ‘bob’
- and count how many times the cork bobs with the waves in a set amount of time
- divide the number of bobs by the time to find the frequency
How can you improve the experiment for ripple tank?
Reduce the effect of random errors by repeating the experiments
Refraction
The waves carry on travelling through the new material
Speculation reflection
When waves are reflected in a single direction by a smooth surface
Give an example of an object that showed speculation reflection
A mirror
A torch shines on a piece of paper. Explain why the surface of the paper appears matt, rather than giving a perfect reflection
- paper has a rough surface
- so each incident ray from the torch has a different normal when it hits the paper
- so angle of incidence is different for each light ray as well as angle of reflection
- the light is reflected in all directions (scattered) so you don’t get a clear reflection
What could you use to produce a thin light ray when investigating refraction of light in different materials?
A ray box
A beam of light shone through a rectangular glass block at an angle and comes out the other side. How many times was the light refracted?
Twice- as it entered and left the block
What happens to the frequency of a wave as it enters a new medium?
It does not change
What happens do your ear drum when it is reached by sound waves?
The sound waves cause your ear drum to vibrate
Describe how and why human hearing changes due to ageing?
As a person gets older, the upper frequency limit of what they can hear decreases, and the sound may need to be louder for the person to hear them. This is mainly due to degeneration of the cochlea or the auditory nerve.
Describe why two cup and string phone works?
- when a person speaks into a cup, they generate sound waves
- which causes the air particles in the cup to vibrate
- these vibrating air particles hit the particles of the cup causing them to vibrate
- these particles hit adjacent particles, passing the sound wave through the cup as a series of vibrations
- these vibrations are transferred in the same way through the string to the cup at the other end of the phone
- the vibrating particles of this cup cause the air particles in the cup to vibrate, generating sound waves that the other person can hear
What is ultrasound?
Sound waves with frequencies above 20kHz
Describe what happens when an ultrasound wave meets the boundary between two media
The ultrasound will be partially reflected at the boundary. Some of it will be reflected, and some of it will be transmitted through the boundary
Give one way that ultrasound is used by boats or submarines
To calculate the depth of water or to locate objects deep in the water
Explain how ultrasound waves can be used to produce an image of a foetus in a prenatal scan
- ultrasound waves will reflect off boundaries outside and within the foetus
- how far away that boundary is can be calculated from the speed of the ultrasound and the time taken to reflect and reach each detector using speed = distance/time
- the ultrasound reflections can be processed by a computer to build up an image of the foetus
Rock Music Is Very UnderValued Xylophone Gamma
Radio waves
Microwaves
Infrared waves
UltraViolet
X-rays
Gamma rays
What kind of EM waves can the human eye detect?
Visible light
Describe how the wavelength and frequency of electromagnetic waves change as the spectrum progresses from radio waves through to gamma rays
Wavelength decreases and frequency increases
What are similarities between all electromagnetic waves?
- they’re all transverse
- they travel at the same velocity in a vacuum
- all transfer energy from a source to an absorber
Give one danger associated with exposure to ultra-violet radiation
- damage to cells
- cancer or radiation sickness
- this is because UV radiation is ionising so it can knock of electrons off atoms in the molecules that make up cells
Is exposure to gamma rays more dangerous than exposure to ultraviolet radiation?
Yes
- gamma rays are more dangerous because they have a higher frequency and so they transfer more energy
- this can cause more damage to tissues in the body
- gamma rays can also pass through through the skin and be absorbed by deeper tissues
How does heat link to infrared radiation?
The hotter an object is the more infrared radiation it gives out
EM wave used for cooking and night vision cameras
Infrared
Explain how microwaves can be used to heat up food
- microwaves are absorbed by water molecules in the food
- transferring their energy to the water
- this causes the water to heat up
- water molecules transfer energy to the rest of the molecules in the food by heating
Explain how an antenna converts incoming radio waves into an electrical signal
- when the antenna absorbs the radio wave
- its energy is transferred to the charges within the antenna
- this causes the charged particles to oscillate, forming an alternating current
How are gamma rays used in cancer treatment?
Gamma radiation is targeted at cancer cells to kill them
What kind of images can convex lenses produce?
Real or virtual
Safety features in cars that are designed to increase collision times
- seat belts
- air bags
Speed of sound in the air
340m/s
What is meant by the ‘braking distance’ of a car?
The distance taken to stop once the brakes have been applied