Topic 4-Waves Flashcards
What is a transverse wave?
Particles travel perpendicular to the direction of the wave. Sea waves.
What is a longitudinal wave?
Particles travel back and forth, parallel to the direction of the wave. Sound wave.
Are electromagnetic waves transverse or longitudinal?
Transverse and do not need a medium to travel through.
What is the frequency of a wave?
Number of waves that pas sa point each second.
What is the period of a wave?
The time it takes for one wave to pass a givev point.
What is the amplitude?
Distance from middle to top/bottom of a wave.
What is the crest?
Top of the wave.
What is the trough?
Bottom of the wave.
What are compressions and rarefactions?
Compressions are regions of high pressure due to particles being close together. Rarefactions are regions of low pressure due to particles being spread further apart.
What two equations tell us the wave period?
What is the triangle that linls velocity, frequency and wavelength?
Explain the core practical on investigating waves.
What is refraction?
The bending or change in direction of light rays when it moves from one medium to another.
What is the interface?
The boundary of the object.
What is the normal?
Line at a right angle to the interface.
What happens when light goes from air to glass or water?
The light bends towards the normal.
What is reflection?
The return of light or sound waves from a surface.
What is the angle of incidence?
Equal to the angle of reflection.
What does transmitted mean?
The wave passes through the material and is not absorbed or reflected.
What does absorbed mean?
The wave disappears as the energy it is carying is transferred to the material.
What is white light and explain prisms?
Light from bulbs or the sun and is made up of every colour in a rainbow. We see these frequencies as different colours. This is why a prism splits up all the coloursas they travel at different speeds so are refracted differently.
Explain the 5 stages of sound entering the ear.
- Sound waves enter the ear canal.
- The eardrum is a thin membrane. Sound waves make it vibrate.
- Vibrations are passed on to tiny bones which amplify the vibrations.
- Vibrations are passed on to the liquid inside the cochlea.
- Tiny hairs inside the cochlea detect these vibrations and creeate electrical signals called impulses.
- Impulses travel along neurones in the auditory nerve to reach the brain.
What is the cochlea?
A coiled tube containing a liquid. It can detect different frequencies of sound reaching the ear. The human ear can detect noises between 20 and 20,000Hz. There are thousands of hairs and each one is connected to a neurone.
What is ultrasound?
Sounds made with higher frequencies than 20,000.
What is infrasound?
Sounds made with lower frequencies than 20.
What is ultrasound used for?
Some animals such as mice communicate using this. Dolphins and bats can detect objects around them using ultrasound waves. The ultrasound waves they make are reflected by things around them and the animals listen for the echo. Ultrasound scans can make images of things inside the body.
How do ultrasound scans work?
What is the difference between S and P waves when it comes to earthquakes?
Why is it difficult to predict when earthquakes will happen?
Movement of plates is sudden and we cannot see what is happening deep inside the earth. REMEMBER TO EXPLAIN HOW EARTHQUAKES WORK OR WHATEVER IN QUESTIONS LIKE THIS.
Why do S and P waves not always travel in a straight line?
Refraction or S waves can reflect. Change in medium.
Explain the difference between longitudinal and transverse waves.
longitudinal need a material for vibrations to pass through whereas EM waves can travel through vacuum.
