PHYSICS WAVES

Year 1 A-level

What is the definition of wavelength?

The minimum distance between 2 points in phase on adjacent waves.

What is the definition of frequency?

The number of wave that pass a certain point per second

What is the definition of amplitude?

The maximum displacement from the equilibrium position. It can be negative or positive.

What is the definition of wave speed?

The distance travelled by a wave per unit time

What is the definition of phase?

The proportion of a wave cycle a given point is at.

What is the definition of period of oscillation?

The time taken for one oscillation of a wave.

What is the definition of displacement?

The distance from the equilibrium position in a particular direction. It can be positive or negative since it is a vector.

What does a wave do?

They transfer energy via oscillations, without net movement of any matter.

What is a mechanical wave?

A mechanical wave needs a medium- a substance that oscillates.

What is a electromagnetic wave?

A transverse wave consisting of oscillating magnetic and electric fields that can travel through a vacuum.

What happens when EM waves and matter interact? Give an example.

It slows the transfer of energy, e.g light waves slow down in water.

What is image resolution?

How clearly an image can be seen.

How can resolution be improved?

Increasing the frequency. This means waves have more energy so could be dangerous.

What is attenuation?

Energy absorbed or scattered within the body, this means the wave loses energy.

What is the frequency range for ultrasound used in medical imaging?

1-3MHz

Why do ultrasound waves partially reflect from the interface between 2 types of tissues?

There is a difference in acoustic impedance (This depends on the density of a medium) of the tissue on each side of the interface.

What is the advantage of low frequency sound?

It travels further than low frequency sound.

What is the advantage of high frequency sound?

It has a higher resolution and therefore gives bats more detailed information of the prey.

What is a transducer?

A device used to emit and detect waves.

Why do transducers emit waves in pulses?

Since its responsible for emission and detection, it can’t do both simultaneously therefore waves are emitted in pulses.

How does the speed of pulses change as a bat gets closer to its prey?

As the bat gets closer, the reflected pulses take less time to return. The bat reduces the time between emitted pulses. This gives more frequent updates to the bat.

What is the intensity of a progressive wave?

The radiant power passing through a surface per unit area.