interference and diffraction (incomplete)

Diffraction

When a wave hits a gap or an obstacle and spreads out

How much diffraction is there when the wavelength is larger than the size of the gap?

Large

The smaller the wavelength hitting the gap…

the less difraction

What happens to wavelength before and after difraction

Stays the same

Why can you hear sounds around a corner but not see where they’re coming from?

Sound has a long wavelength so diffracts more around the building wheres light is a shorter wavelength and wont diffract as much.

Single slit: how would a smaller slit effect diffraction?

More, lower intensity

Single slit: White light shone through the gap

central maxima is white with bangs of colours on either side, red being further away than blue as it has a longer wavelength, therefore a larger angle of diffraction

Monochromatic light-

Light all has the same wavelength / one wavelength

Coherent waves-

Same frequency and wavelength and have a constant phase difference between them

How can non-coherent light be made coherent?

-using a filter

-passing through a single slit

Laser precautions-

-never point at anyone

-place a sign on the door warning of use

-keep lasers pointed at the floor

Constructive interference (when sound is loud, light is bright)

The phase difference is in phase

Destructive interference (when sound is quiet, light is dull)

The phase difference is antiphase

What is it when two sources can travel to a point along different paths which can be different lengths?

Path difference

What happens when the path difference is a whole number of wavelengths?

Arrive in phase and constructively interfere to form a large amplitude (loud/bright)

What happens when the path difference is not a whole number of wavelengths?

Arrive in antiphase (pie radians out of phase) and destructively interfere to cancel eachother out (quiet/dark)

Speed of sound?

C = frequency x wavelength