PHY_10_57_V1_DM_Magnetic properties of a substance

USES OF MAGNETIC MATERIALS  ( NEODYMIUM MAGNETS)

1.        What is a magnet?

2.        What are magnets attracted to?

3.        How are magnets made?

4.        What is the difference between permanent magnets and electromagnets?

5.        State any three areas in which a magnet is used as a sensor.

a)

b)

c)

6.        What is a Seismograph?

7.        Outline three characteristics of neodymium magnets.

8.        How are seismographs important in modern day technology?

Mini experimental questions

Instructional Strategy:

 Part One: Understanding Magnetism

1)      Instruct students to bring the south pole of one bar magnet near the south pole of another bar magnet.  Then bring the two north pole ends together.  Have the students record results on their worksheets.

2)      Now instruct students to bring the south pole of one bar magnet to the north pole of another bar magnet and vice versa.  Have the students record results on their worksheets.

Part Two: Building a Compass

1)      Fill a small bowl or dish about halfway with water.  This will be the body of your compass.

2)      Use the metric end of a ruler to measure a straw.  Using a Sharpie marker, make a mark at about 50 mm.

3)      Using scissors, cut the straw at the line, and keep the 50mm measured portion.

4)      Use a sewing needle that is about the same size as the piece of cut straw.  Magnetize the needle by rubbing the needle anywhere on a bar magnet for about 5-10 seconds, or 100 times.  The needle is now your magnet!

5)      Place the magnetized needle inside the piece of straw.

6)      Place the straw (with the needle inside) onto the surface of the water.  Make sure you did not place the original bar magnet anywhere near the needle and straw or the bowl of water.  Also, make sure the needle and straw do not break the surface of the water.  If they sink, dry them before replacing them back on the surface of the water.  The straw with the needle is now your “compass needle”.

7)      Determine the north and south poles of your compass needle using a bar magnet.  To do this, place the south pole of the bar magnet near your compass needle.  The end that is attracted to the bar magnet is the north pole of your compass needle (because opposites attract), and the other end is your south pole.

8)      Place a small sticker or marker mark on the north pole end to distinguish it from the south pole end of your compass needle.

9)       Observe the compass needle.  Compare it to the direction of a store-bought compass.

Directions:  Use two bar magnets that are the same size to answer the questions below:

1)      Try to touch the two south poles together.  What happened to the magnets?  Do they push each other away from each other or do they pull each other together?

2)      Try to tough the two north poles together.  What happened to the magnets?  Do they push each other away from each other or do they pull each other together?

3)      What happens when you touch the north pole of one magnet to the south pole of another magnet?  Do they push each other apart or pull each other together?

4)      Draw a picture of a bar magnet below.  Label the north and south pole of your magnet.

Directions:  After you have completed building your own compass answer the questions below:

1)      Why do the same poles of two magnets repel each other?

2)      Why do opposite poles of two magnets attract each other?

3)      What does a compass help us to determine?

4)      Why do you think the needle of a compass point towards the north?

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