Direct Current (Electromotive force (emf) (There are 3 emf equations to…
Electromotive force (emf)
There are 3 emf equations to learn as they are SENT DOWN FROM HEAVEN, OMG THEY WILL SAVE YOUR SOUL IN THE EXAM -so PLEASE learn these!
(you will be given this one) e = I(R+r)
V = e -Ir
e = V + v
What's the equation?
Because emf is measured in
you can use these equations.
How do you measure emf?
It is the pd across the terminals of a cell when no current is flowing, so place a voltmeter across the terminals of a cell.
efm is the work done per unit charge of a cell.
What are the circuit rules?
The 3 rules for parallel circuits
flowing through each component is the same.
is the same as the current before it splits into the branches, and the current supplied to each component may be different.
The 3 rules for series circuit
is split between components, so more bulbs in series would be dimmer.
is the same all around the circuit, and the current supplied to each component is the same.
Rules that will help you out SO MUCH in the exam
Kirchhoff's 2 laws
The total emf is equal to the sum of potential drops around a loop, (for any complete loop).
Current entering a junction is the same as the current leaving a junction.
The potential divider