P10 Flashcards
What is Kirchoff’s First Law?
Sum of current in = sum of current out. Law of conservation of charge.
What is Kirchoff’s Second Law?
Sum of EMF = Sum of p.d. across circuit. Conservation of energy to and from charges in an electrical circuit.
What happens to current in series and parallel circuits?
.Same in series .
.Splits in parallel.
What happens to voltage in series and parallel circuits?
.Split in series.
.Same in each loop in parallel.
How do you work out the resistance in a closed loop?
Rt = R1 + R2 + … +Rn.
How do you work out the resistance in parallel?
1/Rt = 1/R1 + 1/R2 + … + 1/Rn.
What is the relationship between Total resistance and resistor size?
Rt = R1+R2/R1R2.
What is true about total resistance?
Lower than smallest resistor’s value.
What happens when you add resistors in series?
Increases net resistance.
What happens when you add resistors in parallel?
Decreases net resistance.
Why are not all cells not equal?
.Produce different EMFs and currents.
What is a determining factor of the magnitude of current produced by a cell?
Internal resistance.
Why is the terminal p.d. less than a power source’s EMF?
.Current = net flow of charge carriers moving inn a direction.
.Have to travel through some material in the power source.
.They do work moving through the power source.
.They lose energy before they leave the cell.
What are the two equations for Internal Resistance?
E = V + Ir.
E = I(R + r).
What happens when you connect cells in series?
Resistance and EMF increase.
