Required Practical– Refraction Flashcards
Give the equipment list for this required practical
Ray box
Protractor
Pencil
Sheet of paper
Ruler
Perspex block (glass block)
What’s the aim of this required practical?
To investigate the refraction of light by a Perspex block
What’s the definition of independent variables and what is the independent variable in this experiment?
The independent variable is what you change each time you repeat the practical. It’s unaffected by all the other variables in the practical. In this practical, the independent variable is the angle of incidence
What’s the definition of dependant variable and what is it in this practical?
The dependant variable is what you’re measuring in the course of the practical. It depends on other variables. In this practical, the dependant variable is the angle of refraction
What are the control variables for this practical?
Use of the same Perspex block.
Width of the light beam.
Same frequency and wave length of the light beam.
What’s the first step of this practical?
Place the glass block on a sheet of paper and carefully draw limes around the block using a pencil: this is to stop you from losing track of the placement of the glass block.
what’s the second step of this practical?
Switch on the ray box and direct a beam of light on the side face of the block
What’s the third step of this practical?
Put marking on the paper at:
Any 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
Any point on the light ray that exited the block (that’s at least 5 cm away from the block)
What’s the fourth step of the practical?
Draw a dashed line normal (at a right angle) to the outline of the block where 2 of the points are (point where light enters block, point where light exits the block)
What’s the fifth step of this practical?
Remove the Perspex block and join the points you’ve marked on the part with three straight lines (point at ray box connects to point where light enters connects to point where light exists connects to 5 cm away point)
What’s the sixth step of this practical?
Replace the block back within its outline and repeat the previous steps again but this time with the ray striking the block at a diff. angle
What’s the seventh step of this practical?
Measure all angles of incidence and refraction and record them in a table of results
What should the result table look like?
On the left column, angle of incidence and on the right column, angle of refraction
What is the final conclusion of this practical?
i and r are always measured from the normal. For light rays entering the glass block, the ray refracts towards the normal line (i > r). For light rays exiting the glass block, the ray refracts away from the normal (i < r). When the angle of incidence was 90 degrees to the glass block, it didn’t refract, it just passed straight through the block (i = r)
