Download Induction

College Physics Interactives: Instructors Guide
INDUCTION, ELECTROMAGNETIC FIELDS AND GENERATORS
Purpose
This Interactive allows you to explore the conditions under which an induced voltage will be produced. Some of the
properties of induced voltages can also be explored.
Using the Interactive
 Configure the Interactive using the FIELD CONTROLS and LOOP CONTROLS or CRANK slider bar on the right-hand
side.
 The Interactive consists of a rotating loop in either a uniform magnetic field (red arrows) or the magnetic field from the
north pole of a bar magnet.
 The induced voltage is measured graphically (top) and numerically (just right of the loop).
The Controls
 Field Type: Select UNIFORM or BAR MAGNET. Under UNIFORM, use the FIELD STRENGTH slider bar to control
its magnitude. You cannot control the strength of the bar magnet.
 Loop Controls: Use LOOP RADIUS to control the size of the loop. You also have options on LOOP MOVEMENT and
ROTATION SPEED for uniform fields only.
 Select CRANK to manually control the loop’s rotation using the CRANK slider bar with either type of field.
Quick Demonstration
 Select BAR MAGNET.
1. What will happen if the magnet is moved closer to, or farther away from, the loop?
a) There will be an induced voltage in the loop that will increase when the magnet is moved closer and decrease
when the magnet is moved farther away.
b) There will be an induced voltage in the loop that will decrease when the magnet is moved closer and increase
when the magnet is moved farther away.
c) There will be an induced voltage in the loop that will not depend on how the magnet moves.
d) There will be no induced voltage in the loop.
 Click and hold on the magnet; drag it up and down. Note the results.
 Click and hold the down arrow on the CRANK slider bar. Note that both the sign and magnitude of the induced
voltage changes. Watch it rotate.
2. Why should the magnitude of the induced voltage change?
a) Because, as the loop rotates, the magnitude of the flux through the loop changes.
b) Because, as the loop rotates, the rate at which the flux through the loop changes varies.
c) Because, as the loop rotates, the magnitude of the magnetic field through the loop changes.
3. Why should the sign of the induced voltage change?
a) Because, part of the time there is an increasing flux and part of the time there is a decreasing flux.
b) Because, as the loop rotates, the rate at which the flux through the loop changes varies.
c) Because, as the loop rotates, the direction of the magnetic field changes.
 Use the CRANK slider bar to orient the loop perpendicular to the bar magnet.
4. What will happen if the magnet is moved closer to, or farther away from, the loop?
a) There will be an induced voltage in the loop that will increase in magnitude when the magnet is moved
closer and decrease in magnitude when the magnet is moved farther away.
b) There will be an induced voltage in the loop that will decrease in magnitude when the magnet is moved closer
and increase in magnitude when the magnet is moved farther away.
c) There will be an induced voltage in the loop that will not depend on how the magnet moves.
d) There will be no induced voltage in the loop.
 Click and hold on the magnet; drag it up and down. Note the results.
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5. What will happen if the size of the loop is increased or decreased?
a) There will be an induced voltage in the loop that will increase in magnitude when the loop is increased
and decrease in magnitude when the loop is decreased.
b) There will be an induced voltage in the loop that will decrease in magnitude when the loop is increased and
increase in magnitude when the loop is decreased
c) There will be an induced voltage in the loop that will not depend on the size of the loop.
d) There will be no induced voltage in the loop.
Interactive: INDUCTION
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