Internal resistance

What is terminal pd less than and what’s their difference?

Will always be less than the emf and lost volts is the difference between them

Describe how internal resistance works

All sources of emf contain some internal resistance, r. When current flows through a power supply, some electric energy get transferred to thermal energy by charges. This appears as energy lost meaning not ALL energy transferred by charges in a circuit from the power supply is available to the rest of the circuit

What is added to get emf?

Terminal pd + lost volts

What do zoomed in cells have and what does it represent?

An imaginary resistor that represents/accounts for lost volts

What does a zoomed in cell look like?

a

What happens to terminal pd in relation to current?

As current increases, terminal pd decreases

As current decreases, terminal pd increases

What ar ethe characteristics of an efficient cell?

Low current, wide, short in length and cooled

What is the equation for lost volts?

Lost volts = Ir

I = current, A

r = internal resistance, Ω

What are the equations of emf?

ℰ = V + Ir

ℰ = I(R+r)

ℰ = emf, V

V = terminal pd, V

I = current, A

r = internal resistance, Ω

R = resistance, Ω

What is the equation for maximum current?

Max current = ℰ / r

ℰ = emf, V

r = internal resistance, Ω