Determining the current through a resistor

In summary, Kirchhoff’s laws are used to determine the current through each resistor and the voltage drop across each resistor in a circuit based on the principles of conservation of energy and charge. They do not directly consider the speed at which the charges pass through the resistors.
  • #1
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Consider the circuit drawn on the attached picture. I have seen a calculation of what the current through each of the resistors is using Kirchoffs laws. Unfortunately I don't qualitatively understand how you are able to determine the current through them.
First of all, but this is probably nothing to worry about, how can you say a current is steady through a resistor when clearly the resistor is making the charges lose kinetic energy?
Secondly, I don't understand the underlying principle used to determine how much current should go through the one resistor and how much through the other. The proces that should determine that would be how fast they are going through each of them since the field will generally avoid piling up charge as much as possible. On the other hand kirchhoffs laws are simply just statements of local conservation of energy and charge, how are they able to explain what the currents should be, when clearly none of them take into consideration how fast the charges pass through the resistors?
 

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Kirchhoff’s laws are based on the idea of conservation of energy and charge. In this circuit, the current entering a resistor is equal to the current leaving it. This means that the total current into the junction must be equal to the total current out of the junction. Since the current entering the junction is known (the voltage source in the circuit), the current through each resistor can be determined by solving a system of linear equations. This process is known as Kirchhoff’s Current Law (KCL). In addition, Kirchhoff’s Voltage Law (KVL) states that the sum of the voltages around any closed loop in a circuit is zero. This law can be used to calculate the voltage drop across each resistor in the circuit. The voltage drop across each resistor is then multiplied by the current through the resistor to calculate the power dissipation in the resistor. Essentially, Kirchhoff’s laws provide a mathematical tool to calculate the current through each resistor and the voltage drop across each resistor in a circuit. They do not take into consideration the speed at which the charges pass through the resistors.
 

1. How do you calculate current through a resistor?

The current through a resistor can be calculated using Ohm's Law, which states that current (I) is equal to voltage (V) divided by resistance (R). This can be expressed as I = V/R.

2. What is the unit of measurement for current?

The unit of measurement for current is the ampere (A), which is defined as the amount of charge passing through a point in one second.

3. How does the resistance of a resistor affect the current?

The resistance of a resistor is directly proportional to the current, meaning that as resistance increases, the current decreases. This relationship is described by Ohm's Law (I = V/R).

4. How do you determine the resistance of a resistor?

The resistance of a resistor can be determined by measuring the voltage across the resistor and the current flowing through it, and then using Ohm's Law (R = V/I) to calculate the resistance.

5. What happens to the current when multiple resistors are connected in series or parallel?

In a series circuit, the current through each resistor is the same, while in a parallel circuit, the current is divided among the resistors. In both cases, Ohm's Law (I = V/R) can be used to determine the current through each individual resistor.

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