Same current through series resistors
In a series circuit the current has only one path.
Three meters in a row
Three resistors are joined one after the other to a battery. One ammeter is put before the first resistor, one between the second and third, and one after the last.
How do the three ammeter readings compare?
What this lesson covers
The idea
In a series combination of resistors the current is the same in every part of the circuit, that is, the same current flows through each resistor.
Three meters in a row
Three resistors are joined one after the other to a battery. One ammeter is put before the first resistor, one between the second and third, and one after the last.
How do the three ammeter readings compare?
- All three read the same
- The first reads the most and the last reads the least
- The last reads the most
Compare the ammeters
Change the battery. Watch the three ammeters.
One path, one current
The current was the same at every place. The charge has only one path to follow, so the same current passes through each resistor.
In a series combination of resistors the current is the same in every part of the circuit, that is, the same current flows through each resistor.
Notes
In a series combination the current is the same in every part of the circuit: the same current flows through each resistor.
Check yourself
Resistors R₁ and R₂ are in series. The current in R₁ is 0.5 A. What is the current in R₂, in A?
Answer: 0.5 A
In a series combination the same current flows through each resistor, so it is 0.5 A in R₂ also.
Where in a series circuit is the current the largest?
An ammeter is placed first at one point and then at another point of a series circuit. What does it read?
Which statement is true for resistors in series?
- It is the same everywhere in the circuit — correct. Yes!
- Just after the cell. The current is the same in every part of a series circuit, also just after the cell.
- Just before it returns to the cell. The current does not get used up. It is the same in every part of a series circuit.
- A smaller value at the second point. The ammeter reading is the same independent of its position in a series circuit.
- The same value both times — correct. Yes!
- A larger value at the second point. The value does not change with the position of the ammeter in the circuit.
- Each resistor gets a different share of the current. That is the parallel connection. In series the same current passes through each.
- The current is largest through the biggest resistor. In series the current is equal in all resistors, however different their resistances.
- The same current flows through each resistor — correct. Yes!