Series and Parallel Circuits Flashcards
True or false? All components connected in series will have the same size current flowing through them.
True
The current is the same at any point in a series circuit
If two cells are connected in series, what is the total potential difference they supply?
The total potential difference is the sum of the individual potential differences of the two cells
Aliyah makes a parallel circuit and puts two bulbs on two separate branches of the circuit. If bulb 1 blows, what change, if any, will there be to the potential difference across bulb 2?
It won’t change - it stays equal to the potential difference across the cell
Matt makes a series circuit containing two resistors connected to a 12V battery. The potential difference across one resistor is 8.7 V. What is the potential difference across the other resistor?
3.3V
The total p.d (12V) is shared across the resistors. So the potential difference must be equal to 12-8.7= 3.3V
Laura wants to measure the current through each of three resistors when they are connected in parallel. How many ammeters will she need to use?
3 ammeters
In a parallel circuit the current is shared between branches, so Laura needs to measure the current through the branch containing each resistor separately
How do you find the total resistance of a series circuit?
By adding up the resistance of each component in the circuit. (You could also work out the total resistance by measuring the current through the circuit and the potential difference across all components, then using the equation V = IR)
Which will have a higher total resistance: two identical resistors connected in parallel, or the same resistors connected in series? Explain why this is the case.
The resistors connected in series will have a higher resistance. When you connect resistors in series you increase their total resistance, as they have to share the source potential difference, and so the potential difference across each resistor is lower. This makes the current through each resistor, and so in the whole circuit, lower. V = IR and so the resistance is higher. When you connect resistors in parallel you lower their total resistance, as the potential difference across each is the same as the source potential difference, and so the total current able to flow in the circuit is increased with each loop that is added.
Geoff makes a set of Christmas tree lights by connecting 200 filament bulbs in series with each other. Each bulb has the same resistance. He connects them to the 230 V mains supply. The current through the bulbs is 0.1 A. What is the resistance of each bulb?
11.5 Ω V = I x R, where R is the total resistance of the circuit. R = V / I = 230 / 0.1 = 2300 Ω
The resistance of each bulb is the same and the sum of their resistances = 2300 Ω
So the resistance of each bulb = 2300 / 200 = 11.5 Ω
