Required Practical: Reflection

Question 1

What equipment do we need for the required reflection practical!

Answer 1

A ray/light box, a protractor, a mirror (preferably with a stand), a sheet of paper, a pencil, ruler, slit cards

Question 2

What is the aim of this required practical (reflection)

Answer 2

To investigate a specular reflection off a smooth surface at different angles and to interstate the rule I = R

Question 3

What is an independent variable and what is the independent variable in this practical?

Answer 3

An independent variable is the variable that you change every time you repeat the steps practical, it is unaffected by any other thing in the practical. For this practical, it’s the angle of incidence

Question 4

What is a dependant variable and what is it in this practical?

Answer 4

A dependent variable is the variable that you measure in a practical. In this practical, it’s the angle of reflection

Question 5

What are control variable used for and what are they in this practical?

Answer 5

Distance from mirror to ray box, width of the beam of light, same frequency/wavelength of the light

Question 6

Why would a thicker beam of light compromise the results of the practical?

Answer 6

The beam of light has to be narrow and thin as it’ll be easier to judge where the centre of the ray is, therefore you wouldn’t lose accuracy due to human error and uncertainty in the measurements taken

Question 7

What is step one of this practical?

Answer 7

Step one is to set up the apparatus. The ray box should be facing the mirror at the first angle you want to measure in

Question 8

What should you do after setting up the ray box and the mirror?

Answer 8

You need to draw a 10 cm line on where you placed your mirror. Beneath it actually. Just to show where your mirror

Question 9

What should you do after you’ve drawn the 10 cm line?

Answer 9

Draw an 8 cm line that bisects (cuts the 10 cm line in half) the 10 cm line at 90 degrees (the line should be perpendicular to half of the 10 cm line). So you should have 4 cm of line in front of your mirror. This line acts as a normal.

Question 10

After you’ve drawn the 8 cm line, what should happen next?

Answer 10

Switch the ray box on with the thinnest slit card in front of where the ray comes out. Aim a beam of light at the place where the 8 cm and 10 cm line intersect (the point of incidence). The beam should hit the mirror

Question 11

When you’ve finally aimed a beam at the mirror and it gives a reflected ray, what should you do!

Answer 11

Mark/trace the reflected line straight from the mirror. It also helps to trace the line that comes out from the ray box (incoming ray). By doing this you can later measure the angles of i and r

Question 12

After you’ve traced both the reflected and incoming ray, what should you do next?

Answer 12

Once they’ve been traced, switch the ray box off and remove the mirror (temporarily) and use a protractor to measure the angle of reflection (found in between normal and reflected ray) and the angle of incidence (between incoming ray and normal).

Question 13

After you’ve measure the two angles, what should happen next?

Answer 13

You should mark your findings down in a table of results (one column for the angle of incidence and one for angle of reflection).

Question 14

After you’ve recorded your first results what should happen?

Answer 14

Repeat this experiment 3-5 more times and record your findings.

Question 15

What are the analysis of results for this practical?

Answer 15

You should find that the results obey the laws of reflection. Your angle of incidence should equal your angle of reflection: if your practical was carried out correctly, this should be the case

Question 16

State two random errors that could’ve occurred in this practical. How would you fix that?

Answer 16

The markings on the protractor may have made the angles difficult to read accurately when it came to measuring them. To fix this, use a protractor with a higher resolution.
Secondly, when it comes to tracing/marking the reflection lines for the incoming ray and the reflected ray, there is a chance that they were inaccurately marked. To prevent this, use a sharp pencil and make sure to trace/mark in the middle of the beam. To double check your lines are accurate, you could have another person check your lines as well

Question 17

List two systematic errors that could’ve happened in this practical

Answer 17

An error could’ve occurred if you drew the normal line incorrectly (not perpendicular to the 10 cm line). To prevent this, use a set square or a protractor to draw and measure your normal line.
If you had a distorted mirror, then it could affect what your angle of reflection turns out to be so make sure they aren’t any blemishes on the mirror or anything

Question 18

What does the risk assume that for this practical look like?

Answer 18

The ray box could get too hot and could cause burns if touched (if anyone gets burned, run burns under cold water for at least five minutes)
Avoid looking directly at the light coming from the ray box as this could damage eyes (stand behind ray box throughout the whole duration of the practical or just avoid looking at the light)
Keep all liquids away from the practical
Take care when using the mirror (smashed mirror could cause injury, and a scratched mirror could mess up your results.