Electricity Principles

What are the three main particles in an atom?

Protons, neutrons and electrons.

What charge does a proton have?

Positive (+).

What charge does an electron have?

Negative (−).

What charge does a neutron have?

Zero/neutral.

What is static electricity?

A build-up of electrical charge in one place.

What is current electricity?

The flow of electrical charge/electrons through a circuit.

What happens between like charges?

They repel.

What happens between unlike charges?

They attract.

What is Coulomb’s Law? (Formula)

F = k(q1q2/d²)

Where F = force between 2 charges (N)

K = 9.0 × 10^9

Q1, q2 = charge on bodies

D = distance between bodies

What happens to the force if one charge doubles?

The force doubles.

What happens to the force if the distance doubles?

The force becomes one-quarter as large.

What is the unit of electrical charge?

Coulomb (C).

What is the charge of an electron?

-1.6 × 10^-19 C

Approximately how many electron charges are in 1 C?

6.3 × 10^18

What is electrical current measured in?

Amperes (A).

What does 1 ampere mean?

1 coulomb of charge flowing per second.

What is the direction of conventional current?

+ → -

What is the direction of electron flow?

- → +

What is electrical resistance?

Opposition to the flow of electric current.

What is resistance measured in?

Ohms (Ω).

Give examples of conductors.

Copper, aluminium, gold, silver, tin and lead.

Give examples of insulators.

Rubber, plastic, glass, porcelain and Teflon.

What is the resistance formula?

R = pl/a

R = resistance (ohms)

P = resistivity

L = length of conductor

A = cross sectional area of conductor

What happens to resistance when wire length increases?

Resistance increases.

What happens to resistance when cross-sectional area increases?

Resistance decreases.

What is a semiconductor?

A material that can behave as either a conductor or an insulator.

Give two examples of semiconductors.

Silicon and germanium.

What is a superconductor?

A material that has zero electrical resistance under suitable conditions, usually at extremely low temperatures.

What is Ohm’s Law?

I = V/R

I = Amps (A)

V = volts

R = ohms