Electricity (unfinished)

Conductors

Materials in which electric charges move relatively freely

Insulators

Materials in which electric charges do not move freely

Give examples of good conductors

Metals like Copper, Aluminum, Silver

Why are metals good conductors?

Because they have a large number of free moving electrons through them

What are some examples of insulators

PVC, polythene, nylon, glass, plastics, rubber, wax

Why can these materials not conduct electricity

They have no mobile charge carriers

Electric current

The flow of electric charge in a particular direction

What must occur in order to maintain an electric current?

The charge must have a continuous path to travel around. E.g. a closed circuit

Why do we say that current flows form positive to negative

Because Ben Franklin thought positive charges were the carriers of charge so we stuck with it, although it is actually the negative charges which are the carriers.

Electric current

The flow of electrons

Electron flow

Negative terminal to positive terminal

Conventional current

Flows from positive terminal to the negative one

Current

Charge on the move

What can be used to measure current

Ammeter

Equation for measuring current

Unit for charge

C - Coulombs

Equation for charge

Alternating current

AC - electric current in which it’s direction and its magnitude change continuously with time and as a result, the voltage level also reverses along with the current

Direct current

Flows in one direction

What is A.C. Used for

Delivering power to houses, office buildings etc.

What is D.C. used for

Batteries, cells

Draw graphs of D.C and A.C.

Why is AC used over DC

AC voltage can be easily stepped up (increased) or stepped down (decreased) using transformers. This is crucial for long-distance transmission because

• High voltage transmission reduces energy loss due to resistance in the wires.

• Stepping up the voltage to very high levels allows for the transmission of large amounts of power with less current, minimizing energy loss.

• Stepping down the voltage to lower levels before it reaches homes and businesses ensures safety.

Potential difference

Aka voltage

the work done, per coulomb, when electrical energy is converted to another form of energy when current flows through a circuit

Equation for voltage / potential difference

What is used to measure e.m.f or potential difference

Voltmeter

What is emf

Electromotive force

Unit: Volts (V)

the driving force behind the cell responsible for propelling the electrons or ions from a state of inertia to kinetic energy in order to move around the circuit.

Resistance

Symbol: R

Unit: Ohms

A measure of the opposition to current flow in an electrical circuit

Power

The rate of conversion when energy is changed from one form to another

Unit: watts

4 equations for power