Calculating Voltage across a Resistor (Parallel Circuit and series circuit)
surely your text (or google!) gives an explanation of how to work with circuits and resistors. Do you have some particular problem, which the concepts can be used to solve?
The basic principle is that
for resistors in series, the current is the same for all of them.
for resistors in parallel, the voltage drop is the same across all of them.
General explanations offered here will likely be no more detailed or comprehensible than what you've already seen. Post a question about a specific circuit and you will very likely get a usable, specific answer.
Steve gave you the recipe.
In series, voltage drops add, currents are the same.
In parallel, currents add, voltage drops are the same.
If I have 2 resistor values 1 being 12 the other 18 how do I calculate the third one
To calculate the voltage across a resistor in both a parallel circuit and a series circuit, you need to understand the basic principles of each circuit configuration.
For a parallel circuit:
1. Determine the total current (IT) flowing through the circuit from the power source by summing up the individual branch currents.
2. Identify the specific resistor you want to calculate the voltage across.
3. Use Ohm's Law, which states that voltage (V) equals the current (I) multiplied by the resistance (R), to calculate the voltage across the resistor: V = I * R.
For a series circuit:
1. Identify the specific resistor you want to calculate the voltage across.
2. Determine the total current (IT) flowing through the circuit by dividing the total voltage (VT) applied to the circuit by the total resistance (RT): IT = VT / RT.
3. Use Ohm's Law to calculate the voltage across the resistor: V = I * R.
Let's work through an example for each circuit:
Example for a parallel circuit:
Suppose you have a parallel circuit with three resistors connected to a power source of 12 volts. The resistances of the three resistors are 4 ohms, 6 ohms, and 8 ohms respectively. You want to find the voltage across the 6-ohm resistor.
1. Calculate the total current:
The branch currents in a parallel circuit add up to the total current. Let's assume the branch currents are I1, I2, and I3.
We can calculate the total current using the equation: IT = I1 + I2 + I3.
2. Calculate the individual branch currents:
The branch currents can be found using Ohm's Law: I = V / R.
The current through the 4-ohm resistor (I1) is: I1 = 12 V / 4 Ω = 3 A.
The current through the 6-ohm resistor (I2) is: I2 = 12 V / 6 Ω = 2 A.
The current through the 8-ohm resistor (I3) is: I3 = 12 V / 8 Ω = 1.5 A.
3. Calculate the total current:
The total current flowing through the circuit is: IT = I1 + I2 + I3 = 3 A + 2 A + 1.5 A = 6.5 A.
4. Calculate the voltage across the 6-ohm resistor:
Using Ohm's Law: V = I * R.
The voltage across the 6-ohm resistor is: V = 2 A * 6 Ω = 12 V.
So, the voltage across the 6-ohm resistor in the parallel circuit is 12 volts.
Example for a series circuit:
Suppose you have a series circuit with three resistors connected to a power source of 24 volts. The resistances of the three resistors are 2 ohms, 3 ohms, and 5 ohms respectively. You want to find the voltage across the 3-ohm resistor.
1. Calculate the total current:
The total current flowing through a series circuit is the same through all components. Let's assume the total current is IT.
2. Calculate the total resistance:
The total resistance of a series circuit is the sum of the individual resistances. Let's assume the total resistance is RT.
The total resistance is: RT = R1 + R2 + R3 = 2 Ω + 3 Ω + 5 Ω = 10 Ω.
3. Calculate the total current:
The total current flowing through the circuit can be found using Ohm's Law: IT = VT / RT.
The total current is: IT = 24 V / 10 Ω = 2.4 A.
4. Calculate the voltage across the 3-ohm resistor:
Using Ohm's Law: V = I * R.
The voltage across the 3-ohm resistor is: V = 2.4 A * 3 Ω = 7.2 V.
So, the voltage across the 3-ohm resistor in the series circuit is 7.2 volts.