required practical 9: experiment 2, refraction of light by a perspex block

what is the independent variable?

angle of incidence

what Is the dependent variable?

angle of relfection

what are the control variables?

• use same perspex block

  • width of light beam

  • same frequency/ wavelength of the light

what is the process for step one?

• take a piece of paper and draw a line across it place the object so one of its sides line up on the line

what is the second step?

• shine a ray of light on the objects surface and trace the incoming and reflected light beams

what happens in the third step?

• draw the normal at the point where the ray hits the object use a protracted to measure the angle of incidence

• use angle of reflection and record these values in a table

what do we also need to take account?

the width and brightness of the reflected ray

what happens in step 4?

repeat experiment for a range of objects

what are some safety considerations?

• The ray box light could cause burns if touched

  • Run burns under cold running water for at least five minute

• Looking directly into the light may damage the eyes

  • Avoid looking directly at the light

  • Stand behind the ray box during the experiment

• Keep all liquids away from the electrical equipment and paper

• Take care using the mirror

  • Damages on the mirror can affect the outcome of the reflection experiment

what are some systematic errors?

• 90 degrees draw incorrectly use set square to draw perpendicular lines

• mirror distorted, angle of reflection effected, be sure to wipe blemishes

what are some random errors?

• point incoming from reflected beam may be inaccurately marked, use sharp pencil to mark middle of beam

• use protractor with high resolution, because of difficulty reading angles