# Finding the current and the voltage across each resistor

• Lopez
In summary, the voltage is 24V and the resistors have values of 270 ohms, 330 ohms, 1.2k ohms, and 1.2k ohms. The currents for each resistor were given as IR1=20, IR2=20, IR3=10, and IR4=10. After combining the two 1.2k ohm resistors, the effective resistance becomes 0.6k ohms and is in series with R1 and R2. This allows for the calculation of the currents.
Lopez

## Homework Statement

Find the current and the voltage across each resistor.

volts is 24v
R1=270 ohms
R2=330 ohms
R2=1.2k ohms
R4=1.2k ohms

## The Attempt at a Solution

This is not a homework its more like a study guide.
He gave us the answer for just the currents which are
IR1=20
IR2=20
IR3=10
IR4=10
But not sure how he got that.
this is what i did but don't know how to go from there:
(270+330)|| (1.2k||1.2k)
600||600
R=300

#### Attachments

• practice.png
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Hi Lopez. Welcome to physics forums!

The 270 and 330 are in series with the 600, not parallel.

Chet

Lopez said:
(270+330)|| (1.2k||1.2k)
Having reduced the (1.2k||1.2k) to an effective 0.6k, what is the relationship of that in the circuit to R1 and R2?

ahh yes there was the problem,after 1.2 k and the other 1.2k were combined it becomes one resistor in series with the (r1 and R2). Thanks!

ohms
V=24V
I=V/R
I=24/300
I=0.08A or 80mA

Based on the given information, it appears that the circuit is a series-parallel circuit with two parallel branches. To find the current and voltage across each resistor, we can use Ohm's Law (V=IR) and Kirchhoff's Laws.

First, we can calculate the total resistance of the circuit by using the parallel resistance equation: 1/Rt = 1/R1 + 1/R2 + 1/R3 + 1/R4

1/Rt = 1/270 + 1/330 + 1/1200 + 1/1200
1/Rt = 0.0069 + 0.003 + 0.00083 + 0.00083
1/Rt = 0.01146
Rt = 1/0.01146
Rt = 87.2 ohms

Next, we can calculate the total current in the circuit by using Ohm's Law: I = V/R

I = 24/87.2
I = 0.275A or 275mA

Now, we can use Kirchhoff's Current Law (KCL) to find the current through each resistor. KCL states that the sum of the currents entering a node (or junction) must equal the sum of the currents leaving the node. In this case, the current entering the node is the total current (0.275A) and the currents leaving the node are the individual currents through each resistor.

Using KCL for the left node:

0.275A = IR1 + IR2
IR1 + IR2 = 0.275A

Using Ohm's Law, we can solve for IR1 and IR2:

IR1 = V/R1
IR1 = 24/270
IR1 = 0.0889A or 88.9mA

IR2 = V/R2
IR2 = 24/330
IR2 = 0.0727A or 72.7mA

Using KCL for the right node:

0.275A = IR3 + IR4
IR3 + IR4 = 0.275A

Using Ohm's Law, we can solve for IR3 and IR4:

IR3 = V/R3
IR3

## 1. What is the difference between current and voltage?

Current is the flow of electric charge through a circuit, while voltage is the potential difference that drives this flow.

## 2. How can I find the current and voltage across each resistor?

To find the current, you can use Ohm's Law (I=V/R) and calculate the current based on the voltage and resistance of the resistor. To find the voltage, you can use Kirchhoff's Voltage Law, which states that the sum of the voltage drops in a closed loop circuit must equal the voltage source.

## 3. What factors affect the current and voltage across a resistor?

The current across a resistor is affected by the resistance of the resistor and the voltage applied to it. The voltage across a resistor is affected by the current flowing through it and the resistance of the resistor.

## 4. Can the current and voltage across a resistor be different from each other?

Yes, the current and voltage across a resistor can be different. This is because the current is dependent on the resistance and voltage, while the voltage is dependent on the current and resistance. It is possible for one to change while the other remains constant.

## 5. How do I measure the current and voltage across a resistor?

To measure the current, you can use an ammeter, which is placed in series with the resistor. To measure the voltage, you can use a voltmeter, which is placed in parallel with the resistor. Both instruments can provide accurate readings of the current and voltage across a resistor.

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