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Flashcards in magnetic and chemical effects of electrical currents Deck (15)
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1

explain the magnetic effect around an electric current

All currents have a magnetic field around them. All the cables connecting electrical appliances to the mains in your home will have magnetic fields around them, and so do the large electricity power lines you can see on pylons outside. A straight wire has a circular magnetic field around it. A coil of wire has a magnetic field around it, that is the same shape as a bar magnet. If the conventional current flows the other way, the magnetic field will be in the opposite direction. As you move further away from the wire, the magnetic field gets weaker, which is why the lines are drawn further apart. These types of magnets are called electromagnets. They are temporary magnets as they can be turned on and off with the current. Normal bar magnets are permanent magnets because it is very difficult for them to lose their magnetism.

2

what is the motor effect

When two magnets are close together, they affect each other and produce a force. The same happens when any two magnetic fields are close together. If a wire carrying a current is placed in a magnetic field a force is produced. This is called the motor effect. The direction of the force will depend on the direction of the magnetic field and the direction of the current in the field.

3

how can one increase the force in an electromagnetic motor

Increase the size of the current. Increase the strength of the permanent magnet.

4

define electroylisis

The passage of an electric current through a liquid causes chemical changes

5

simply put what is an electromafnet and how can the electromagnetic strength be increased

When an electric current flows in a wire it creates a magnetic field around the wire. By winding the wire into a coil we can strengthen the magnetic field. Electromagnets are made from coils like this. Making an electromagnet stronger We can make an electromagnet stronger by doing these things: wrapping the coil around an iron core adding more turns to the coil increasing the current flowing through the coil.

6

describe an electric motor

An el­ectric motor is all about magnets and magnetism: A motor uses magnets to create motion. If you have ever played with magnets you know about the fundamental law of all magnets: Opposites attract and likes repel

7

define an electric motor

An electric motor is an electric machine that converts electrical energy into mechanical energy

8

what is the commuter in an electric motor

A commutator is a mechanism used to switch the input of certain AC and DC machines consisting of slip ring segments insulated from each other and from the electric motor's shaft. A commutator is the moving part of a rotary electrical switch in certain types of electric motors or electrical generators that periodically reverses the current direction between the rotor and the external circuit.

9

what are the brushes in an electric motor

A brush is a device which conducts current between stationary wires and moving parts, most commonly in a rotating shaft. Typical applications include electric motors

10

define primary and secondary electric cells

A primary cell is a battery that is designed to be used once and discarded, and not recharged with electricity and reused like a secondary cell (rechargeable battery)

11

explain the difference between primary and secondary electric cells

As a primary cell is used, chemical reactions in the battery use up the chemicals that generate the power; when they are gone, the battery stops producing electricity and is useless. In contrast, in a secondary cell, the reaction can be reversed by running a current into the cell with a battery charger to recharge it, regenerating the chemical reactants

12

descibe in detail a primary electric cell

All galvanic cells consist essentially of a negative electrode and a positive electrode in an electrolytic solution. The solution contains ions (electrically charged atoms or groups of atoms) that promote chemical changes in the electrode materials. When a cell is connected to an electrical circuit, electrons flow from the negative electrode through the circuit into the positive electrode. The flow of electrons, or electric current, is produced by a difference in potential between the electrodes. The difference in potential is measured in volts and is generally referred to as voltage. It is caused by an electromotive force (emf) resulting from the relative strength with which atoms of each electrode attract electrons. The atoms of the positive electrode exert a stronger attraction for electrons than do the atoms of the negative electrode. When a current is established between the two electrodes, chemical reactions at each electrode proceed spontaneously, supplying free electrons to the circuit from the negative electrode and, at the same time, taking up free electrons from the circuit at the positive electrode.

13

describe in detail a secondary electric cell

This type of cell is rechargeable—that is, the chemical reactions that produce electricity in the cell can be readily reversed to restore the materials in the cell to their original condition. (The chemical reactions in a primary cell either are difficult to reverse or cause irreversible changes in the cell's internal structure.) A secondary cell is recharged by forcing an electric current through the cell in a direction opposite to that of the current produced by the cell itself. Devices called rechargers make it possible to recharge some secondary cells with household electrical current.

14

diagram of an electric motor

15

an electric motor has 6 main parts

A simple motor has six parts:

Armature or rotor
Commutator
Brushes
Axle
Field magnet
DC power supply of some sort