Physics aos 3 electrical physiccs i think k

Proton to electron ratio in a neutral atom

Number of electrons = number of protons

Proton to electron ratio in ions

Number of electrons ≠ number of protons (due to loss or gain of electrons)

Electrons in negative ions

Have an excess of electrons (electrons gained)

Electrons in positive ions

Have a deficit of electrons (electrons lost)

Elementary charge (e)

Charge of one electron = -e; charge of one proton = +e

Why metals are conductors

Electrons are free to move through the lattice of positive ions, as they are weakly attracted to the nucleus

Why non-metals are insulators

Electrons are tightly bound to their nucleus and cannot move readily between atoms

Charge of object that gains electrons

Net negative charge

Charge of object that loses electrons

Net positive charge

Net charge

Sum of charges gained/lost when electrons move between objects

Ion

An atom that has gained or lost electrons

Electric current

Flow of electric charge carried by electrons (in wires) or ions (in solutions)

What is/are the requirement/s for current

Complete conducting pathway (closed loop), so electrons can flow

All circuits require

An energy source, wires, and a circuit element (so something can happen)

Electric current (definition)

Flow of electric charge

Size of electric current is equal to?

Rate(speed) of flow of charge

Measurement for current

Amperes (A)

Conventional current

Direction of current from positive to negative terminal

What is electron flow

The movement of electrons from negative to positive terminal

What do you need for current to flow in an electrical circuit?

A continuous loop from one terminal of a power supply to the other via a conductor

What happens to electrons in a current

Energy from power source pushes electrons; they repel each other, so they transfer energy without touching, like a bicycle chain

What is an electrical circuit?

a path of conductive material forming a closed loop through which charge can flow

A battery transforms {{c1::stored chemical energy}} into {{c1::electrical potential energy}}

Transforms stored chemical energy into electrical potential energy

How batteries convert energy

converts chemical energy into electrical potential energy by maintaining a voltage (difference in electric charge)

Battery terminal charges

Negative terminal = excess electrons, Positive terminal = deficit of electrons; chemical reactions maintain this difference

How batteries run out of charge

Chemical reactions are mostly used up, so there’s not enough energy to push electrons through the circuit

Potential difference

Energy gained or lost by each unit of charge between two points

Measurement of potential difference

Measured in volts (V) using a voltmeter connected in parallel

When does charge flow?

when there the potential difference between two conductive points is not zero

Voltmeter connection

Connected in parallel, with negative lead towards negative terminal and positive lead towards positive terminal

Rate of electrical potential energy

Converted into other forms of energy in a circuit (work is done)

Power

Rate at which energy is converted by a device; measured in watts (W)

Ammeter

Measures current in amperes and must be connected in series

Meaning of rate

Quantity measured over time

Conventional vs actual current

Conventional flows + to –, but actual electrons flow – to +

Units for energy

Joules (J)

Symbol and unit for charge

Q, Coulombs (C)

Symbol and unit for current

I, Amperes (A)

Units for resistance

Ohms (Ω)

direct current

charge flows in one direction

alternating current

electric charge reverses periodically

What is voltage drop?

the voltage drop across a circuit element is a measure of the amoun tof energy that is transformed in that circuit element for each coulumb of charge passing through it