snells law Flashcards
what does the refractive index (n) show us?
how optically dense a material is
what does n give us a value of?
for how the speed of light in that materials relates to the speed of air
what is the refractive index?
the property of a material
material that are less dense have….
a lower refractive index
materials that have a high optical density….
have a higher refractive index
what is the equation for snells law?
n= sin(i)/ sin(r)
what is the independent variable in the snells law practical?
angle of incidence
what is the dependant variable in the snells law practical?
the angle of refraction
what are the control variables in the snells law practical?
use of the same perspex block, width of the light beam, same frequency of the light beam
what is the ray box used for?
to provide a narrow beam of light to reflect in the mirror
what is the protractor used for?
to measure the light beam angles
what is the sheet of paper used for?
to mark with lines for angle measurement
what is the pencil used for?
to mark perpendicular line and angle lines on paper
what is the ruler used for?
to draw lines on paper
what is the perspex rectangular block used for?
to retract the light beam
1st step?
place the glass block on a sheet of paper and draw around the block using pencil
2nd step?
draw a dashed line normal to the outline of the block
3rd step?
use a protractor to measures the angles of incidence to be studied and mark these lines on the paper
4th step?
switch on the ray box and direct a beam of light at the side of the block at the first angle to be investigated
5th 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 exists the block
a point on the exit light ray which is about 5cm away from the block
6th step?
remove the block and join the points marked with 3 straight lines
7th step?
replace the block within its outline and repeat the process for rays striking the block at the next angle
what do you do with your results?
plot a graph of sin i on the y axis against sin r on the x axis
what will the refractive index be equal to?
the gradient of the graph
