Required Pratical (Reflection and Refraction)

Equipment needed

What is the aim of this experiment

-Reflection of light by different types of surfaces

-Refraction of light by different substances

What is the control variables

-Using same glass block

-Width of the light beam

-Same frequency/wavelength of light

Describe experiment with apparatus

1)Using a ray box, lens and a slit to produce a narrow ray of light

2)Take a piece of A3 paper and draw a straight line down the centre using a ruler

3)Use a protractor to draw a line at right angles called normal

4)Place a glass block against the first line so that the normal is near centre of block

5)Draw around the glass block and turn off all lights in room

5)Use the Ray box to direct a Ray of light so it hits the block at the normal which is the incident ray

6)Adjust the Ray box to change the angle of incidence so at a certain angle we see a Ray reflect from surface of block. We also see another Ray leaving the block from the opposite side called transmitted Ray

7)Mark the path of incident ray and reflected Ray with crosses. Also mark math of transmitted Ray

8)Turn on room light and switch off the Ray box

9)Then remove glass block,

10) Draw in incident ray and reflected ray

11)Draw transmitted ray so it meets the postion of block

12)Draw a line to show path of the transmitted ray through the glass block

13)Use protractor to measure angle of incidence and reflection. Then angle of refraction

14)Do whole experiment again with different material block like plastic(perpex)

Why is it important to switch off ray boxes if not in use

As they get hot

What could we use instead of a ray box

A laser but it’s more dangerous

What should be the results of this experiment

1)We should find out angle of incidence and reflection are the same in both glass and plastic as they both don’t depend on material

2)However the angle of refraction will be different with plastic than with glass as angle of refraction is different with different materials

What is systemic errors with experiment

1)An error could occur if 90 degree line are drawn incorrectly

What is the Random errors in experiment

1)The points for incoming and reflected ray may be inaccurately marked-Fix using sharpened pencil and mark in middle of ray

2)The protractor resolution may make it difficult to read angles-Fix by using protractor with high resolution

What are some safety considerations

-Ray box may cause burns if touched- run under cold water if so

-Looking directly into Ray box may damage your eyes

-Keep liquids away from electrical equipment and paper

-Take care when using glass block