ELECTRICITY AND MAGNETISM

Section D

An object can eith

An object can either be _______ or ______ charged

positively or negatively

Briefly explain what happens when a Glass/Perspex rod is rubbed with glass

The glass/perspex rod becomes positively charged because the cloth possesses a more significant attraction for electrons than the glass rod.

Explain charging by induction

Charging by induction is a process where a neutral object becomes charged without direct contact with a charged object. It relies on the redistribution of charges within the neutral object due to the presence of a nearby charged object. When a charged object is brought near a neutral object, the charges within the neutral object rearrange themselves, creating a temporary separation of charges.

What is meant by the term ‘electric field’?

An electric field is a region in space where a charged object experiences a force.

Describe 1 hazard of static electricity

Hazards of static electricity involve the building up of charges

1. Static electricity can generate sparks, which are a common ignition source for flammable liquids, gases, and dusts. For example, static sparks can ignite gasoline fumes at a gas station.

   Examples:

   In industrial settings, static electricity can be a major cause of fires and explosions in industries like flour mills or when handling flammable chemicals.

2. Lightning

   Lightning is essentially a large-scale static discharge. Within a storm cloud, water molecules collide and rub together, creating a buildup of static electricity. This charge separation eventually becomes large enough to cause a massive spark, or lightning bolt, to discharge the accumulated energy,

Describe 1 useful application of static electricity

1. Photocopying

   A metal drum is given a strong electric charge, and the image to be copied is reflected onto the drum. The areas where light hits the drum lose their charge, creating a latent image. 

2. Electrostatic Painting

   The object being painted is given an electric charge, while the paint is given the opposite charge. This causes the paint particles to be attracted to the object, ensuring an even, uniform coating

3. Dust Collectors/Precipitators

   The dust or smoke particles in the air are given an electrostatic charge through an ionization process. The charged particles are then attracted to oppositely charged collection plates within the precipitator. The charged particles stick to the collection plates, effectively removing them from the air stream. 

Opposite forces ______ while like forces _______

attract;repel

Define the term ‘conductor’

A conductor is a material that allows electricity (or thermal energy) to pass through it

What is an ‘insulator’?

An insulator is a poor conductor of heat. This means that it does not allow heat/electricity to pass through it

Differentiate between the current flowing within a metal and the current flowing in an electrolyte/ semiconductor

Electric current in a metal is solely caused by a flow of electrons while current in a semiconductor or electrolyte is caused by the flow of 2 things:

Electrolyte: positive and negative ions

Semiconductor: electrons and holes (areas where electrons are missing)

Differentiate between ‘conventional current’ and ‘electron flow’

Electron flow refers to what actually takes place in a conducting wire, which is the flow of electrons from the negative to the positive terminal.

Conventional current is the generally accepted idea of the flow of electrons in a circuit. This states that electrons flow from the positive terminal to the negative terminal.

_____ = Current x Time

Charge

Current is measured in?

Amperes

Coulumbs is the unit for?

Charge

State 2 differences between alternating and direct current

1. Direct current only flows in one direction while alternating current reverses (flows in two directions)

2. Direct current cannot be stepped up or down by a transformer while alternating voltage can

3. Dc Current has a fixed voltage while Ac current does not

4. Dc current represented on a graph is a straight line while ac current forms a wave like structure

____ = 1/T

f

What is meant by the ‘frequency’ on a graph?

The amount of cycles that take place in one second (or given unit of time)

Differentiate between a magnetic material and a non-magnetic material

These are materials that are attracted to magnets and can be magnetized. On the other hand, these are materials that are not attracted to magnets and cannot be magnetized.

List FOUR examples of magnetic materials

Iron, Nickel, Cobalt, Steel and Magnadur

Give 2 differences between permanent and temporary magnets

Define a ‘magnetic field’

A region in space in which a magnetic material will experience a force.