p5.1 - grey(yr11) Flashcards
p5.1.3 + p5.1.4
when does reflection occur?
when a wave hits a hard, smooth surface
what is refraction?
the change in direction of waves as they travel across a boundary between two different media
what is a medium?
any space which is full of matter of the same density
what 3 features change in waves when they cross a boundary between two different media?
- speed changes
- direction changes
- they slightly bend
describe the behavior of waves when they travel from a high-density medium to a low-density medium
velocity - increases
frequency - remains same
wavelength - increases (same as velocity)
normal - bends away from normal (more velocity)
what is one way to remember how the wavelength changes during refraction?
- must balance (v = w x f) out
as frequency always remains constant
describe the behavior of waves when they travel from a low-density medium to a high-density medium
velocity - decreases
frequency - remains same
wavelength - decreases
normal - bends towards normal (slows down0
how does the velocity/wavelength/frequency change during reflection?
(and why)
all remain the same
- as it carries on travelling through the same medium (travel through air, reflected off mirror, carry on through air)
- and the medium determines the speed + wavelength of a wave through it
what is the reason you can see an object?
the object is emitting/reflecting light
how do you draw the normal line?
it is perpendicular (90 degrees) to the boundary
what does the law of reflection show?
the angle of incidence is equal to the angle of reflection
what 3 things can happen to a sound wave at a boundary?
- reflected
- transmitted/refracted
- absorbed
what factor affects what happens to a sound wave at a boundary?
the density of the regions either side of the boundary
what is ultrasound and why is it useful?
- wavelength with high frequency ( > 20 000 Hz)
- useful as it has a small wavelength
- and can be focused into a beam
why does the colour remain same during refraction?
as the frequency remains same (and colour is dependant on frequency)