reflection and refraction Flashcards
when does reflection happen?
when a wave changes direction back to the same medium at a boundary
what is reflection normally represented on?
a ray diagram
what is the normal?
an imaginary line which we measure angles from that is always perpendicular to the boundary
what is the angle of incidence?
the angle the incidence ray makes with the normal
what is the angle of reflection?
the angle the reflected ray makes with the normal
what is the law of reflection?
the angle of incidence is equal to the angle of reflection
when does refraction happen?
when a wave changes direction when travelling into a different media at a boundary
what of a wave changes when refracted?
the speed and wavelength- not the frequency
the normal is at what type of angle to the boundary?
right angles
from less dense (eg glass to air) what happens to the light?
it bends TOWARDS the normal
from more dense to less dense (eg glass to air) light….
bends AWAY from the normal
when light passes into a denser substance what happens to the rays?
the rays will slow down
what is the independent variable in the refraction of light practical?
shape of the block
what is the dependant variable in the refraction of light practical?
direction of refraction
what are the control variables in the refraction of light practical?
the width of the light beam and the same frequency/ wavelength of the light
why will we need a ray box?
to provide a narrow beam of light to reflect in the mirror
why will we need a protractor?
to measure the light beam angles
why will we need a sheet of paper?
to mark with lines for angle measurement
why will we need a pencil?
to mark perpendicular lines and angle lines on paper
why will we need a ruler?
to draw lines on paper
why will we need a rectangular block, semi- circular block and a prism?
to refract the light beam
1st step of the practical?
place the glass block on a sheet on paper and draw around it using a pencil
2nd step?
switch on the ray box and direct a beam of light at the side face of the block
3rd step?
mark on the paper:
a point on the ray close to the ray box
the point where the ray enters the block
the point where the ray exits the block
a point on the exit light ray which is a distance of about 5cm away from the block
