Measuring angles with a protractor Use this tutorial

Measuring angles with a protractor Use this tutorial for Part A 1

What do we use to help us? A protractor Here is a standard protractor like you use in the classroom. 2

When we use a protractor, we need to line it up correctly. You need to make sure the protractor is lined up correctly. Is this ready to measure the angle? 3

Were you right. . . . . it wasn’t Look for the upside down ‘T’ in the middle of the straight line on your protractor. This needs to be exactly on the vertex of your angle. 4

We need to remember. . . It doesn’t matter which way round the angle is, you ALWAYS need to line the upside down ‘T’ to the vertex of the angle. 5

Now you are ready. Read from the 0°, and follow the inner set of numbers. 6

Now you are ready. You can call this angle ABC. A C B Read from the 0°, and follow the inner set of numbers. You always want to read the angle from zero up to the line. Whether it is the inner or 7 outer set of numbers.

Once you reach 30° you need to be careful!!! A C B You then need to look at the 1° markings on the outer set of numbers. 8

What does it measure? A C B This angle measures 35°. 9

Part B • The Law of Reflection 10

The Law of “REFLECTION” The Law of Reflection states that- " the angle of incidence (incoming ray) equals the angle of reflection (outgoing ray)" The law works for FLAT, PLANE surfaces only. The angles are measured from a perpendicular line to the surface called a NORMAL

On your paper • Use the information from the previous slide to draw and label the… 1. incident ray and label 2. the normal 3. the reflected ray 4. the angle of incident 5. the angle of reflection Do this for both examples 12