# Voltage across resistors in series and parallel

• TrolliOlli
In summary, the conversation discusses the concept of voltage and resistance in a circuit. The main question is why the voltage across bulb B is the same as the voltage across the 10 ohm resistor, even though their resistances may be different. The answer is that in parallel circuits, the voltage remains the same while the current may differ. This concept also applies to series circuits, where the current is the same while the voltage may differ.

#### TrolliOlli

So I must be missing some crucial knowledge in my knowledge of electrostatics because I simply don't understand how this works. I'm given a circuit like this:

[PLAIN]http://img3.imageshack.us/img3/8730/circuiti.png [Broken]

and I find out the voltage across bulb B is the same as that across the 10 ohm resistor.

I was under the impression that, since we know V = IR and we know the current across B is the same as the current across the 10 ohm resistor the Voltage would be different assuming B has a resistance other than 10 ohms. What am I missing here?

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The voltage is the same, not necessarily the current. Branches in parallel have the same voltage.

Doc Al said:
The voltage is the same, not necessarily the current. Branches in parallel have the same voltage.

Would that also apply to two resistors in series? If I simply had a battery with two resistors in series would their voltage be equal regardless of whether or not their resistors were equal?

TrolliOlli said:
Would that also apply to two resistors in series? If I simply had a battery with two resistors in series would their voltage be equal regardless of whether or not their resistors were equal?
Things in parallel have the same voltage; things in series have the same current.

## 1. What is the difference between voltage across resistors in series and parallel?

In a series circuit, the voltage across each resistor is equal to the total voltage of the circuit. This means that the voltage is divided among the resistors, resulting in a lower overall voltage across each individual resistor. In a parallel circuit, the voltage across each resistor is the same as the total voltage of the circuit. This is because the current has multiple paths to flow through, resulting in each resistor receiving the full voltage.

## 2. How do I calculate the voltage across resistors in a series circuit?

To calculate the voltage across each resistor in a series circuit, you can use Ohm's Law, which states that V = IR (voltage = current x resistance). First, calculate the total resistance by adding up the individual resistances in the circuit. Then, use the total resistance and the current in the circuit to calculate the voltage across each resistor.

## 3. How do I calculate the voltage across resistors in a parallel circuit?

To calculate the voltage across each resistor in a parallel circuit, you can use Ohm's Law, which states that V = IR (voltage = current x resistance). In a parallel circuit, the current is split among the different paths, so you will need to calculate the total current flowing through the circuit. Then, use this total current and the resistance of each individual resistor to calculate the voltage across each resistor.

## 4. What happens to the voltage across resistors in a series circuit when one resistor fails?

In a series circuit, the failure of one resistor will result in the entire circuit failing. This is because the circuit is broken, and no current can flow through. Therefore, the voltage across all resistors in the circuit will be zero.

## 5. Can the voltage across resistors in a parallel circuit be higher than the total voltage of the circuit?

No, the voltage across resistors in a parallel circuit cannot be higher than the total voltage of the circuit. This is because the voltage is divided among the different paths, and the total voltage is used up by all the resistors in the circuit. However, the individual voltages across each resistor may be different, depending on their resistances.