Charge and current

Current is measured by…

Ammeter (in amps)

Potential diff is measured by…

Voltmeter (in volts)

Current in series…

Is the same in every position.

Voltage in series…

Is shared between components.

Current in parallel…

Is shared between branches.

Voltage in parallel…

Is the same across each component as the output voltage.

Which way around a circuit do electrons travel?

Because early day physicists got it wrong:

• Conventional current = positive - negative

• Real life / modern day = negative to positive

  Because electrons are attracted to the positive terminal and repelled by the negative terminal.

What does 1 ampere represent?

6.25 × 10^18 electrons passing a point in a circuit each second.

What does one coulomb of charge contain?

6.25 ×10^18 electrons

What charge does 1 electron have?

1.6 ×10^-19 C

Define charge

No. Of electrons x charge of 1 electron

What is Kirchoff’s first law

For any point in an electrical circuit, the sum of currents into that point is equal to the sum of the currents out of that point

What is kirchoffs second law

In a complete loop within a circuit, the sum of all voltages across components must equal the sum of all voltages across the components in the same loop

What is number density

A measure of the number of free electrons per cubic metre of material

What is the equation for mean drift velocity

I = Anev

What does each letter mean in I = Anev

I = current

A = area

n = number density

e = elementary charge

v = mean drift velocity

What is the elementary charge

1.6 ×10^-19

What is emf (ξ)

Amount of energy put into the circuit per coulomb of charge

What is potential difference (V)

Amount of energy taken out of the circuit per coulomb of charge

What is the emf equation

V = ξ - Ir