"Scientific Inquiry: Why Electric Motors Rotate" From Compass to Maglev Train PPT Courseware 3

Description

"Scientific Inquiry: Why Electric Motors Rotate" From Compass to Maglev Train PPT Courseware 3

Review introduction

Experiment description: There is a magnetic field around the current-carrying wire, which has a magnetic effect on the magnet.

The energized wire can deflect (move) the magnet, indicating that the magnet is affected by magnetic force

Reverse thinking - can a magnet move a current-carrying wire?

New knowledge exploration

1. The effect of magnetic field on current-carrying wires

(1) Conjecture:

A current-carrying wire experiences a force in a magnetic field.

(2) Design experiments:

Summary: The effect of magnetic field on electric current

1. The current-carrying wire is affected by __ in the magnetic field

2. The direction of the force exerted on the current-carrying wire in the magnetic field is related to ______ and ____

3. Only change __________ or ___________, the direction of the force on the current-carrying wire is _________, if _________ changes the direction of the current and the direction of the magnetic field, the direction of the force will be _______

2. Principle of electric motor

The movement of the energized coil across the equilibrium position

Tip: How to make the coil continue to rotate clockwise after crossing the equilibrium position?

The force on the coil close to the S pole is always upward

The force on the coil near the N pole is always downward, so the coil can continue to rotate in the clockwise direction.

Discussion: How to achieve the above situation?

Change the direction of current or magnetic field in time

(that is, crossing the equilibrium position) thereby changing the direction of the force

A and B are brushes

Function: Contact with the half ring to form a closed circuit between the power supply and the coil.

E and F are commutators (two semicircular copper rings):

Function: Change the direction of the current in the coil in time so that the force direction is always the same and the coil keeps rotating.

Practice in class

1. A current-carrying conductor in a magnetic field ( )

A. It must be affected by the magnetic force

B． May be affected by magnetic field forces

C. Must not be affected by magnetic field forces

D． None of the above statements are correct

2. To change the steering direction of the DC motor, you can use ( )

A. Change the direction of the current, keeping everything else unchanged

B. Change the direction of the magnetic field, keeping everything else unchanged

C. Increase the current intensity

D. Change the direction of current and magnetic field at the same time

3. Which of the following statements is correct ( )

A. An electric motor is a machine that converts mechanical energy into electrical energy.

B. An electric motor is a machine that converts electrical energy into mechanical energy.

C. DC motors use the rotation of coils to generate current.

D. Changing the direction of the current in the coil can change the speed of the motor coil rotation

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"Scientific Inquiry: Why Does the Electric Motor Rotate" From Compass to Maglev Train PPT Courseware 2:

"Scientific Inquiry: Why Does the Electric Motor Rotate" From Compass to Maglev Train PPT Courseware 2 Electric Motor (1) Main components: ________ and ________. (2) Principle: The magnetic field has a _________ effect on the current-carrying conductor, and the direction of its effect is the same as _________, _______..

"Scientific Inquiry: Why Electric Motors Rotate" From Compass to Maglev Train PPT Courseware:

"Scientific Exploration: Why the Electric Motor Rotates" From Compass to Maglev Train PPT Courseware The Effect of Magnetic Field on Current Stretch out your left hand so that your thumb is perpendicular to the other four fingers and in the same plane as your palm. Put your left hand into the magnetic field , let the magnetic field lines be vertical..

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Update Time: 2024-11-25

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