Magnets, magnetic fields and electromagnets
Grade 8 Science Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
Read this first
Teacher's electromagnet test (example data)
coils paper clips lifted 10 3 20 6 30 9 Bo adds more coils to a teacher's electromagnet and the pattern continues. How many clips would it lift with 60 coils?
Use this
Field diagram of a bar magnet, N pole on the left and S pole on the right. Field lines leave the N pole, curve around outside the magnet and enter the S pole; arrows on the lines point from N to S. Point A is 1 cm from the N pole, where the lines are close together. Point B is 6 cm above the middle of the magnet, where the lines are far apart.
Where is the field stronger, and how do you know, Jun?
- At B, since its lines spread over a larger area
- At A, since the lines are close together there
- The same at both, since field lines cannot cross
- At B, since it is above the middle of the magnet
Use this
Field diagram of a bar magnet, N pole on the left and S pole on the right. Field lines leave the N pole, curve around outside the magnet and enter the S pole; arrows on the lines point from N to S. The compass is 2 cm to the left of the N pole.
Which way does the compass needle's north end point, and why, Kira?
- Toward the magnet's N pole, since a north end is pulled to north
- Away from the magnet's N pole, along the field lines
- Up the page, to the geographic North Pole
- It keeps spinning, since two poles are near
What will these two magnets do, and what in the diagram shows it, Luz?
- Nothing happens, since the lines do not meet in the gap
- Push apart: the lines from the two N poles bend away
- Pull together until the field lines cross in the gap
- Pull together, since both of the facing ends are N poles
What a magnet picks up (example data)
object material picked up paper clip steel yes nail iron yes foil aluminum no wire copper no spoon plastic no pencil wood no Which statement does the table support, Milo?
- A magnet picks up only the small, light objects
- It picked up only the iron and steel objects
- A magnet picks up only the shiny, smooth objects
- A magnet picks up every metal object it touches
Noah adds an iron washer and an aluminum washer to the test. What should the magnet do, using the table?
- Pick up the iron washer but not the aluminum one
- Pick up the aluminum washer, since it is lighter
- Pick up both, since both are metal
- Pick up neither, since washers are small
A paper clip near a magnet (example data)
distance from the magnet (cm) clip jumps to the magnet 1 yes 2 yes 4 no 8 no What does the table show about the magnet's pull on a paper clip, Pia?
- The pull is the same at each distance tested
- The pull works just when the clip touches the magnet
- It acts across a gap and weakens with distance
- The pull gets stronger the farther away the clip is
Two bar magnets push apart with their ends facing. Ren turns one magnet around. What happens, and why?
- They pull together: now unlike poles face each other
- They push apart harder, since the poles now face the other way
- They push apart the same, since turning does not change poles
- They spin around each other without touching
Can Tala cut a bar magnet to get a piece with just an N pole?
- Yes, by cutting off the N end of the magnet
- Yes, by grinding off the S end of the magnet
- Yes, by cutting the magnet exactly in the middle
- No: every piece has both an N and an S pole
Zee's compass is near a bar magnet's S pole, and the needle's north end points at the magnet. Why?
- A compass's north end is attracted to a south pole
- The needle is iron, so it sticks to the magnet
- The magnet is pointing north, so the needle follows
- North ends of compasses are attracted to north poles