Date __________
Partners _______________________________________________________
APHY101 – Lab – Magnetism
Experiment #1 – The magnetic field of permanent magnets
Equipment: bar magnet, compasses, magnaprobe
Procedure:
1. Place the bar magnet on the table and set the compass near the north pole of the magnet.
Move the compass to various positions around the magnet and draw its field on the figure below.
2. Place the compass next to the bar magnet’s north pole and slowly move the compass away
from the magnet. Stop moving the compass when it is not aligned with the magnet’s field
anymore and record this distance from the magnet. __________ cm. Repeat for the south pole.
___________ cm. What is the cause of the change in direction?
3. Hold the bar magnet in your hand and determine the shape of the field using the magnaprobe.
Make sure that you pass the magnaprobe over and under the magnet. Is this a more accurate
“map” of the bar’s magnetic field compared to the one using the compass? Explain.
Experiment #2 – Electromagnetic Induction
Equipment: bar magnets, large coil, galvanometer, wires
Procedure:
1. Connect the large coil to the galvanometer with the wires. Quickly insert the north pole of the
magnet into the coil and describe the response of the galvanometer.
Remove the magnet and describe the response.
Repeat using the south pole of the magnet.
Compare the galvanometer’s response to both ends of the magnet.
2. Now move the north pole of the magnet slowly into the coil. What is the relationship
between the rate at which you move the magnet into/out of the coil and the meter’s response?
Explain in terms of Faraday’s Law.
3. Repeat step 1 but with two magnets. Explain the difference in the meter’s response for two
magnets instead of one.
What happens if you insert the magnets with one north pole and one south pole together?
Explain.
Experiment #3 – Transformer Basics
Equipment: coil set, batteries, galvanometer, wires
Procedure:
1. Connect one 400-turn coil to the galvanometer with the wires. Place the other 400-turn coil
next to the first coil such that you can look through both coils. Briefly connect the second coil to
the batteries and record the approximate value on the meter. _______ What is the value on the
meter as you hold the wires on the batteries? ________ What happens to the meter when you
disconnect the wires from the batteries? _____________________________________________
Explain the meter’s responses.
2. Now place the iron bar inside both coils and make your connection to the battery. What
effect does the metal bar have on the current induced in the first coil? Why would an iron bar
make any difference?
3. Place the 200-turn and one 400-turn coil next to each other with the iron bar inside both coils.
Connect the 200-turn coil to the galvanometer and the 400-turn coil to the batteries. What is the
meter’s response? _______________________________________________________________
Now connect the 400-turn coil to the galvanometer and the 200-turn coil to the batteries. What is
the meter’s response? ____________________________________________________________
Based on what you observed, which situation is a step-up transformer and which is a step-down?
Experiment #4 – The swinging wire
Equipment: Thick wire, horseshoe magnet, ring stand, clamp, pencil, batteries, wires
Procedure:
1. Connect the wires to one battery and record the response of the wire.
2. Now reverse the direction of the current and record the response of the wire. Explain these
responses.
3. Repeat step 1 but keep the current direction constant and change the direction of the magnetic
field by flipping the magnet over. How do these responses of the wire compare to those found in
step 1?
4. Connect the circuit to two batteries. Compare the amount of deflection when you use two
batteries to when you used only one. Why would you expect the deflection to be different in this
case?
Experiment #5 – emf
Equipment: Battery, hand generator, small light bulb, wires
1. Wire a series circuit with the generator and light bulb. Connect the circuit to the battery and
describe what happens.
2. Hold the handle of the generator and describe what happens. Why is there a change in the
bulb’s brightness?
3. Rotate the handle quickly in the same direction as it is turning until the light turns on. Is the
generator’s emf > or < the battery’s emf? Explain.
4. Rotate the handle slowly in the opposite direction until the light turns on. Why is the bulb
brightness not the same in each case?