Transcript (PPTX)

Electromagnetics
for 8th grade
Activity Guide
• Challenge: Discuss (5-10 minutes)
• Generate Ideas and Multiple Perspectives (instructor choice)
• Research and Revise (and Test Your Mettle)
– Activity 1: Review the relationship between electricity and
magnets (5-10 minutes)
– Activity 2: Copper coil motor (10 minutes) – this can be
conducted as a demonstration or each group can construct a
copper coil motor
– Activity 3: Create a Current Detector (15-20 minutes)
– Activity 4: Create an Electromagnet (15-20 minutes)
– Activity 5: Complete Data Chart (10-15 minutes)
• Go Public: Revisit challenge (instructor choice)
Teacher Tips
• The magnetic motor can be a demonstration/review or a
hands-on activity for your students.
• You may need to use the needle nose pliers to straighten
the ends of the copper coils used in the magnet motor. BE
CAREFUL not to bend the coil.
• The current detector shows dramatic response when
testing the battery and much less dramatic response with
the electromagnet. It does show a response, though!
• These experiments show the relationship between
electricity and magnets.
•
A magnet that is moved past a copper coil causes the electrons to move,
moving electrons create electricity.
• This activity is designed for 6 groups of 4 students each.
– Each group of students will do the same activities.
– You will prepare a bin of materials for each of the 6 groups.
Teacher Prep
• Assemble materials from next page
– Set up 6 bins of the same materials for 3-4 students at each of 6 tables
• 4 D-cell batteries
• 4 D-cell battery holders
• 2 pieces of 3 meter copper wire with insulation stripped off ends (they are coiled on
cardboard)
• 1 piece of ½” diameter PVC tube
• 2 jumper cables
• 1 compass
• 1 roll clear tape
• 1 bar magnet
• 1 12 cm iron nail
• 1 plastic bowl
• 1 box of 100 paper clips
• 1 Electromagnetic chart
• 2 safety pins
• 1 copper wire coil
• 1 metric ruler
– Set up 6 stations, 1 at each table.
Materials
• 24 D-cell batteries
• 24 D-cell battery holders
•
• 12, 3-meter piece of 18-24 gauge
•
insulated wire with ends stripped off •
• 12 jumper cables
•
• 6 compasses
• 6 rolls clear tape
• 6 bar magnets-plain
• 6 bar magnets with North and South
Poles marked
• 6 12 cm iron nail
• 6 plastic soup bowls
• 6 boxes of 100 paper clips
• 6 copies of Electromagnet Data Chart
– stored in mechanical room filing
drawer on bottom left
• 6 PVC pipes ½-inch diameter x 4-inches
long
6 copper coils (with ends stripped)
12 large safety pins
6 pens/pencils
6 metric rulers
Location of All Materials
Drawer 4a1:
• 4 boxes labeled bar magnets
• 9 ½” diameter PVC tubes
• 10 6” iron nails
• 8 bags of 100 paper clips
• 28 mechanical pencils
• 9 compasses
Drawer 4a2:
• 12 rolls clear tape
• 7 ceramic bar magnets
• 16 jumper cables
Drawer 4a3:
• 20 D cell batteries
• 6 sets of insulated copper wire (2 4-meter
lengths rolled on cardboard)
• 8 rulers
• 36 D-cell batteries
• 1 plastic box containing 8 copper coils,
16 safety pins, 8 rubber bands, 1 pair needle nose pliers
Drawer 4a4:
• 8 plastic bowls
Worksheet
Challenge
• The president of a local office supply
company, STEMco, has asked your class to
design and build an executive desk toy.
– The toy must be capable of some type of motion
OR light up, but cannot contain batteries or be
connected to an electric outlet.
– The president’s son owns a magnet factory, so the
toy MUST contain at least one magnet.
Guiding Question
• How are electricity and magnetism related?
– How can we detect electric current with a magnet,
compass, and battery?
– How can we create an electromagnet?
– What can you do with a simple motor?
• Review –
– What is electricity?
– What is an electromagnet?
Activity 1: How are electricity and
magnets related? (5-10 minutes)
• A magnet can induce an electric current when
moved through a coil of copper wire.
– A magnet that is moved past a copper coil causes
the electrons to move.
– Electricity is the flow (movement) of electrons.
• A magnet can also reverse the flow of
electrons (electricity) in a copper wire.
Activity 2: Create Copper Coil Motor
(10 minutes)
• Materials needed:
– 1 D cell battery
– 1 coil of copper wire
– 1 bar magnet
– 2 safety pins
– 1 rubber band
The teacher can conduct
this part of the activity as a
demonstration for review
or engagement!
Attach doubled rubber band to battery.
At each end of battery, insert one safety
pin in between rubber band and battery.
Make sure
both safety
pins are level
at the top.
Put a magnet under the battery - in
line with the long axis of the battery.
Insert copper coil in the small loops at
the top of each safety pin.
You may need to use the needle
nose pliers to straighten the ends
of the copper coil. BE CAREFUL not
to bend the coil.
Very lightly spin the coil. What happened?
Now reverse the magnet. What happened?
Take Apart Copper Coil Motor
• Take apart the coil motor.
– Remove magnet from battery.
– Remove copper coil from safety pins.
– Remove safety pins
– Remove rubber band.
• Return materials to your bin.
Activity 3: Creating a Current Detector
(15-20 minutes)
Materials for each group
of 4 students:
• 2 jumper cables
• 2 pieces 18 gauge wire
3 meters long (with
ends stripped)
• Small compass
• D-cell battery
• D-cell battery holder
• Strong magnet
• 4 inch piece of ½-inch
diameter PVC pipe
• Clear tape
Wrap 3-m wire around compass
• Wrap loops tightly around middle of compass:
– Leave 40 cm at the end.
– Wrap from North to South. The wire must stay at the
middle of the compass
– TIP: you may want to tape the wire on the compass to
hold it in place as you wrap.
Placed D-cell battery in battery holder.
Line up the compass on your desk
• Make sure North points North and lines up
with the wire loops.
• This is your current detector!
Connect one end of wire to the D-cell
• Connect the compass to the D-cell battery
using jumper cable. One end of the jumper
cable on the compass wire, one end on the
battery.
Touch other end of wire to D-cell
• Connect a 2nd jumper
cable to the battery
terminal.
• Touch the free alligator
clip to the bare end of
the wire.
• Observe what happens
and record your
observations in your
Electromagnet chart.
• Disconnect the jumper
cables from the battery
and compass.
Wrap 3-m wire around PVC tube
• Leave at least 50 cm of wire at each end.
• Wrap tightly but DO NOT overlap the wires.
• TIP: you may need tape to hold the wire in
place as you wrap.
Connect one wire on current detector
• Use a jumper cable to connect one wire on
the current detector to one wire on the PVC
tube.
• Use a second jumper cable to connect the
other wire on the current detector to the free
wire on the PVC tube.
It is very important that
the cardboard tube is as
far away from the
compass as is possible!!!
SLOWLY insert a magnet labeled with North
and South into the PVC tube and pull out.
Insert and pull out.
• Observe and record what happens to the compass
needle.
• The compass must be FLAT to work. You may need to
hold it in place.
• Note: South is inserted into the tube in the image below.
Predict ….
• What will happen to the compass needle if you
reverse the magnet before you insert it into the tube,
North first?
• Now test your prediction. Remember the compass
must be FLAT to work.
• Note: North is inserted into the tube
• Disconnect all wires and straighten wire that
was wrapped around PVC. Wrap it around
cardboard and return materials to your bin.
Conclusions – for your worksheet
1. Describe what happened to the compass
when current ran through the wire.
2. Describe what happened when you reversed
the position of the bar magnet in the tube.
3. In what way is the compass needle’s
movement evidence of a current in the wire?
4. What do you think produced a current in the
wire?
Activity 4 - Create an Electromagnet
(15-20 minutes)
Materials per group of 4 students:
• 4 D-cell batteries
• 4 D-cell battery holders
• Large iron nail (16 cm)
• 100 metal paper clips in a
plastic bag
• Small plastic container
• 2 jumper cables
• 3 meters of 24 gauge copper
wire with ends stripped off
• Electromagnet Chart
Wrap wire around nail
• Leave approximately 25 centimeters of wire
free at each end.
• Wrap the wire around the nail tightly, making
your coils as close together as possible. Do
NOT overlap the wire!!!
• Stop at the end of the nail. (You may have
more than 25 centimeters of wire left at that
end.)
Insert batteries in battery holders
• Make sure – end of battery is at – end of
battery holder.
Connect wire to battery
• Use a jumper cable to attach one end of the
wire to one end of the battery.
• Connect another jumper cable to the free end
of the battery and the free end of the wire.
• This is an electromagnet.
Test your electromagnet
• Place one end of the
electromagnet in a bowl full of
paper clips.
• Count the number of paper
clips and record in your
Electromagnet Data Chart.
• Repeat this test 2 more times.
• Record in Electromagnet Data
Chart. Calculate average # of
paper clips picked up.
• Disconnect one end jumper
cable from the battery.
Add 2nd battery
• Clip another battery in series onto your
electromagnet.
• Re-test it and record the number of paper clips you
can pick up.
• Repeat this test for a total of 3 trials.
• Record in Electromagnet Data Chart. Calculate
average # of paper clips picked up.
• Disconnect one jumper cable from battery.
Add 3rd battery
• Clip a third battery in series
onto your electromagnet.
• Re-test it and record the
number of paper clips you
can pick up.
• Repeat two more times for
a total of 3 trials.
• Record in Electromagnet
Data Chart. Calculate
average # of paper clips
picked up.
• Disconnect one jumper
cable from battery.
Add 4th battery
• Clip a fourth battery in series onto your electromagnet.
• Re-test it and record the number of paper clips you can pick
up.
• Repeat two more times for a total of 3 trials.
• Record in
Electromagnet Data
Chart. Calculate
average # of paper
clips picked up.
• Disconnect one
jumper cable from
battery.
Activity 5: Complete data chart
(10-15 minutes)
• Calculate the average number of paper clips
picked up for each total battery voltage and
record in Electromagnets Data Chart.
• Graph your results.
• What happened to the electromagnets
strength when you added more volts?
Go Public: Revisit the Challenge
• The president of a local office supply
company, STEMco, has asked your class to
design and build an executive desk toy.
– The toy must be capable of some type of motion
OR light up, but cannot contain batteries or be
connected to an electric outlet.
– The president’s son owns a magnet factory, so the
toy MUST contain at least one magnet.
Vocabulary
• Electromagnet - An arrangement of wire wrapped
around a core producing a temporary magnet
• Electricity – the low of electrons
• Induce – cause to happen
• Magnet – object that attracts certain metals
(especially those containing iron)
• Maglev – magnetic levitating system.
– A transportation device that relies on electromagnets
to propel it.
– Repulsion and attraction work to push and pull the
train along.