Physics - Electricity and magnetism

Describe the forces between magnetic poles

Explain that magnetic forces are due to interactions between magnetic fields

Describe the forces between magnets and magnetic materials

Describe induced magnetism

Induced magnetism is the temporary magnetism that occurs in a material when it is brought near a magnet or when a magnetic field is applied to it. This magnetism is not inherent to the material and disappears once the external magnetic field is removed.

It is caused by the alignment of the material's atomic or molecular magnetic moments in response to the external magnetic field.

Describe methods of magnetization

* By stroking
* Placing solenoid inside a coil of wire with d.c

State the difference between magnetic and nonmagnetic materials

State the differences between the properties of temporary magnets and permanent magnets

Temporary magnets and permanent magnets have distinct properties:


1. **Magnetization:** Temporary magnets can be magnetized and demagnetized easily, while permanent magnets retain their magnetization over a long period.
2. **Source of Magnetism:** Temporary magnets are usually made from soft magnetic materials, such as iron or steel, which can be easily magnetized. Permanent magnets are made from hard magnetic materials, like neodymium or ferrite, which have strong intrinsic magnetism.
3. **Strength of Magnetism:** Permanent magnets have a stronger magnetic field compared to temporary magnets. This allows them to attract or repel other magnets with greater force.
4. **Durability:** Temporary magnets can lose their magnetism quickly when the external magnetic field is removed. Permanent magnets, on the other hand, retain their magnetism for a longer time, making them more durable.
5. **Applications:** Temporary magnets are commonly used in applications where magnetism is required temporarily, such as electromagnets in electric bells or relays. Permanent magnets find applications in various devices like speakers, motors, and generators.

It's important to note that these are general differences, and specific types of magnets may have additional or unique properties.

magnetic field

region in which a magnetic pole experiences a force

the direction of a magnetic field at a point is the direction of the force on the N pole of a magnet at that point

Draw the pattern and direction of magnetic field lines around a bar magnet

Describe the uses of permanent magnets and electromagnets

Charge

* positive and negative charges
* positive charges attract negative charges
* measured in coulombs
* electric field as a region in which an electric charge experiences a force

Describe simple experiments to show the production of electrostatic charges

by friction and to show the detection of electrostatic charges

Explain that charging of solids by friction…….

involves only a transfer of negative charge (electrons)

Describe an experiment to distinguish between electrical conductors and insulators

Recall and use a simple electron model to explain the difference between electrical conductors and insulators and give typical examples

electric current

the charge passing a point per unit time; recall and use the equation

I = Q / t

Describe the use of ammeters (analogue and digital) with different ranges

Know the difference between direct current (d.c.) and alternating current (a.c.)

Define electromotive force

the electrical work done by a source in moving a unit charge around a complete circuit

measured in volts (V)

E = W/Q

Define potential difference (p.d.)

* the work done by a unit charge passing through a component
* p.d. between two points is measured in volts (V)
* V = W/Q

Describe the use of voltmeters (analogue and digital) with different ranges

Resistance

R = V/I

a) resistance is directly proportional to length

(b) resistance is inversely proportional to cross-sectional area

Recall and use the equation for electrical power

P = IV

Recall and use the equation for electrical energy

E = IVt

Define the kilowatt-hour (kWh) and calculate the cost of using electrical appliances where the energy unit is the kWh

Series vs Parallel

State the advantages of connecting lamps in parallel in a lighting circuit

Explain that the sum of the currents into a junction is the…….

same as the sum of the currents out of the junction

Describe the action of a variable potential divider