Physics EoY Y9 Revision Flashcards (sound and light)

What is the scientific name for the separation of light into its different colours when it passes through a prism?

dispersion

Why does dispersion happen?

Because the different spectral colours travel at different speeds through dense materials such as glass

What is the definition for frequency?

The amount of waves passing a point per second (measured in Hertz)

What is the wavelength of ultraviolet waves? (Prefixes not standard form)

400nm - 10nm

What is the frequency of ultraviolet? (standard form)

8 × 10^14 Hz to 3 × 10^16 Hz

What are the four uses of UV?

Sterilisation of water, detecting real/fake bank notes, flourescent lights, sun beds.

What are the 5 risks of UV?

Ionising radiation, has enough energy to ionise atoms in cells, can damage DNA, can cause mutations or cancer, sunburn.

What are the 3 Ls about (relative to radio waves and microwaves on the left of the electromagnetic spectrum)?

Long wavelength, Low frequency, Low energy.

What speed to the electromagnetic spectrum waves travel at in a vacuum?

3 × 10^8 m/s.

How is skin cancer caused?

By excessive exposure to UV radiation from the sun, causing DNA damage to skin cells. If this damage is not repaired by the body’s internal DNA repair machinery, then faulty cell replication can occur - triggering the abnormal growth of cells - which eventually become cancers.

What is the equation for wave speed?

wave speed = frequency x wavelength

Why do sounds become quieter the further away you are from the sound being made?

Because the further you are from the source, the more spread out the sound waves become, and some of the sound wave’s energy is absorbed by the air particles as it passes through, meaning that the amplitude decreases.

Explain how sound is transferred through a solid, liquid or gas in your ear.

Sound waves pass through a gas when they go through the ear canal, then they pass through the eardrum as vibrations in a solid. Later on, in the cochlea, they pass as vibrations in a liquid.

Name the different parts of the ear starting from the left and going to the right.

pinna, ear canal, ear drum, ossicles (hammer, anvil and stirrup), cochlea, neurons (auditory nerve)