1 Ampere’s experiments

Interaction between the conductor and current, Ampere's experiments

1

To explain the physical meaning of magnetic induction vector based on problem solving and modern technological advances (magnetic levitation train, etc.)

2

Set the power supply to 1 V, switch on, and
observe what happens to the foil.
Increase the power supply to 2 V.
What happens?
Now reverse the connection to the power supply.
What happens?
Finally, reverse the magnet. What happens to the
foil?

1. First, arrange the connections so the current is passing down both strips of foil. Set the power supply to 1 V. Switch on and describe what happens.
2. Increase the power supply to
2V. What happens now?
3. Arrange the connections so that
the current is passing up both
strips of foil. What happens?
4. Finally arrange the connections so the current is passing up one foil and down the other. What is the result?

(a) Two parallel
conductors carrying currents I1 and I2
(b) Magnetic field B1 produced by I1 (Field produced by I2 is not shown.)
B1 points into page at position of I2.

(a) Parallel currents in
the same direction exert an attractive
force on each other.
(b) Antiparallel
currents (in opposite directions) exert
a repulsive force on each other.

a shows two
unlike (anti-parallel) currents, one flowing into the page,
the other flowing out of the page. Their magnetic fields
circle round. The diagram shows the resultant field, and the repulsive
forces on the two wires.

b shows the same idea, but for two like
(parallel) currents. In the space between the two wires, the magnetic fields cancel out. The wires are pushed together.

Conceptual Questions

1. What is the nature of force between two parallel current carrying wires in the same direction?

2. Why do two parallel wires repel?

3. Do perpendicular wires exert magnetic force each other?

4. How does current affect magnetic field?

What has been learned
What remained unclear
What is necessary to work on