Experiment: Create a series circuit with a 20-volt battery and four 20-ohm resistors, as shown. Measure the current.
1. Based on the voltage and current, what is the resistance of the circuit?
(Hint: Use Ohm’s law.)
2. Ohmmeters measure resistance. Remove the battery and attach the terminals of the Ohmmeter (OO) to the ends of the circuit, where the battery used to be attached.
What is the resistance?
3. Make a rule: How do you calculate the total resistance of a series circuit?
4. Extend your thinking: Replace the battery. Turn on Show current, and remove one resistor. Why would it be a problem if your household appliances were connected in a series circuit?
1. Using Ohm's law (V = IR), we can calculate the current in the circuit by dividing the voltage by the total resistance of the circuit. In this case, the voltage is 20V and the total resistance is the sum of all four resistors connected in series, which is 20 ohms each. Therefore, the total resistance of the circuit is 20 + 20 + 20 + 20 = 80 ohms.
By rearranging the formula, we get: I = V / R
Plugging in the values, we get: I = 20V / 80 ohms = 0.25A
So, the current in the circuit is 0.25 amperes.
2. When using an Ohmmeter to measure the resistance of the circuit, we have already calculated that the total resistance of the circuit is 80 ohms.
3. The total resistance of a series circuit is calculated by summing up the individual resistances of all the components connected in series.
4. When one resistor is removed from a series circuit, the total resistance of the circuit decreases. This means that the current flowing through the circuit will increase. In a household appliance, if the devices were connected in a series circuit, removing one appliance would affect the entire circuit by increasing the current flowing through the remaining appliances. This could lead to potential overheating or damage to the remaining appliances. Additionally, if one appliance were to fail, it could interrupt the entire circuit, causing all appliances to stop working. Therefore, connecting household appliances in a parallel circuit is more practical and safer.