AP PHYSICS 2M8 L4 PA1.

Name: ______________________________________ Date: ________________________



Student Exploration: Magnetic Induction

Vocabulary: current, induced magnetic field, magnetic field, Pythagorean Theorem, right-hand
rule


Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

1. Where does the needle on a compass normally point? North


2. What will happen to the compass needle if you hold a magnet close to it? The needle points
towards the magnet


Gizmo Warm-up
A compass is a useful tool for measuring the direction
of a magnetic induction field—more commonly called
a magnetic field—because the needle's northern tip
points in the direction of a field. In the Magnetic
Induction Gizmo™, you will use compasses to
measure the magnetic field caused by a current.

The SIMULATION pane shows an overhead and front
view of a table with a wire threaded vertically through
its center, perpendicular to the surface of the table.
Check that the Current is set to 0 amps.

1. Drag a compass to several different locations on the SIMULATION pane. Where does the

compass needle point? North

The effect you see is due to Earth's magnetic field.


2. Slowly increase the Current value from 0 to 60 amps. Describe what happens: The
compass point moves


3. Move the compass around on the table. What do you notice? The compass point is always
at a tangent to the metal rod in the center of the board




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, Activity A:
Get the Gizmo ready:
Observing
 Set the Current to 0 amps.
induction

Goal: Use compasses to determine the direction of magnetic
field induced by a current in a wire.

1. Predict: Place the compasses in a circle around the wire as
shown at right. What do you think will happen as you slowly
drag the Current slider all the way to the right?

The compasses will start to form a circle around the wire


2. Test: Use the Gizmo to test your prediction. Describe the results: The compasses formed a

circle around the wire to show the magnetic field



3. Observe: Look at the Front view on the SIMULATION pane.

In which direction is the current moving through the wire? From bottom to top through the

board

(Note: The current direction shown is the direction of positive charge. In reality, electrons
move in the opposite direction through the wire.)


4. Predict: Scientists use the right-hand rule to predict the direction
of an induced magnetic field—or a magnetic field created by a
current. To use the right-hand rule, position your right hand so
that the thumb points in the direction of the current. The magnetic
field lines wrap around the wire in the same direction as the
fingers of your right hand.

If the current was pointed down, will the induced magnetic field

be clockwise or counterclockwise? Clockwise


5. Test: Set the Current to -60 amps.

A. In which direction is the current now moving through the wire? Top to bottom through
the board

B. What is the direction of the induced magnetic field? Clock wise




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