Magnets and electromagnets, lesson 4

1. Magnets and electromagnets lesson 4 Target To learn about variables, values and relationships in a magnets investigation September 23, 2009

2. Key words Variable Value Relationship

3. What variables are there in a set of books?

4. colour of cover size of the book number of pages pictures or not colour of writing or black and white What variables are there in a set of books? What values are there?

5. Key words Variable Value Relationship = something that changes = how the variable is measured = a link between the variables Notes

6. Let's look at some shapes: What are the variables ? shape size colour What are the values ? triangle or rectangle small, medium or large red or blue

7. What is the relationship between the shapes? Discuss this with the person next to you. Remember discussion is important. What do you think?

8. Let's look at some shapes: What is the relationship between these shapes. Shape – red shapes are squares, blue ones are triangles. The next shape is blue . Can you predict the shape? Yes = triangle

9. Let's look at another set of shapes: What are the variables ? What are the values of these variables? What is the relationship ? Shape, colour and size Triangle or circle, red or blue, small or large

10. Let's look at another set of shapes: What are the variables ? What are the values of these variables? Can you make any connections or relationships ? Shape, colour and size. Triangle or circle, red or blue, small or large. Small = Red Large = Blue

16. Answers Variables Speed of truck, mass of digger, strength of concrete on the bridge, width of movable arm on the digger Values Speed = mile per hour, Mass of digger = kilograms, Strength of concrete = Newtons per cm to crush the bridge Width of arm = metres Relationships High speed = more damage High mass = more damage Stronger bridge = less damage Wider arm = less damage

17. Investigating magnet strength Variables Values Shape and size of the magnet. Number or mass of paper clips picked up. Bar or horse shoe magnet, mass of magnet in grams. Number of paper clips. Method of testing – add paperclips to the magnet until they fall off. Count the number of clips and record results on a table.

18. Investigating magnet strength Variables Values Shape and size of the magnet. Number or mass of paper clips picked up. Bar or horse shoe magnet, mass of magnet in grams. Number of paper clips. What do your results show? Is there a relationship between the variables?