5.3 EMF, Cells And Circuits Flashcards
What is the EMF?
The total work done per unit charge in moving charge from one terminal of the cell to the other.
E = W/q measured in joules per coulomb or volts.
What is a primary cell?
A battery or cell that runs out of energy and must therefore be discarded when it runs out of energy.
What is a secondary cell?
A battery or cell that can be recharged and used again.
What is terminal voltage?
The voltage at the terminals of a batter or cell it is given by V = E-Ir where E is the EMF of the battery and r is the internal resistance.
What is the total power delivered by a battery?
EI.
What are series circuits?
One in which resistances are connected one after the other so the same current runs through each.
How is resistance added in a series circuit?
The effective resistance of resistors in series is the sum of the individual resistances.
What is the sum of the potential differences in a series circuit?
The same of the potential difference across resistors in series is equal to the EMF of the battery.
What are parallel circuits?
One in which resistances are connected in parallel so they are sharing the same potential difference.
What is the total current delivered by a battery in a parallel circuit?
E/Rt where Rt is the total resistance of the parallel combination of the resistors.
How are resistances added in parallel circuits?
1/Rt = 1/R1 + 1/R2
What is a thermistor?
A resistor in which resistance decreases as the temperature increases.
What is a light dependent resistor?
A resistor in which the resistance decreases as the incident intensity of light increases.
What is Kirchoff’s current law?
The total current into any junction equals the total current out of the junction - a consequence of charge conservation.
What is Kirchoff’s loop law?
In each closed loop the sum of the EMF’s equals the sum of the voltages across all resistors in the loop - a consequence of energy conservation.
