Content

• Steps
• Advice

Before you can calculate the voltage of the resistor, you must first determine what type of circuit is being used. If you need a review of the basics or need a little help understanding different types of circuits, start with Part One. If not, skip it and go to the text about the type of circuit you need to deal with.

Steps

Part 1 of 3: Understanding electrical circuits

1. 

   Learn about circuits. Think of the circuit in this way of thinking: imagine you are pouring a bag of corn kernels into a bowl. Each grain of corn is an electron (electron), and the flow of the grain flowing into the bowl is an electric current. When talking about lines, you describe it by saying how many particles are moving per second.

2. 

   
   
   Think about electric charges. Electrons carry a "negative" charge. That is, they attract (or move towards) a positively charged object, and push (or move away from) a negatively charged object. Because they are all negative, the electrons are always trying to push each other, spreading out whenever possible.

3. 

   
   
   Understand voltage. Voltage is the difference in charge between two points. The larger the charge difference, the stronger the two ends. Below is an example of a conventional battery:
   • In the battery, chemical reactions take place and electrons are accumulated. These electrons travel towards the negative end, while the positive tip remains in a state almost empty (They are called the cathode and anode). The longer this process is, the greater the voltage between the two ends.
   • When connecting wires between the cathode and the anode, suddenly, the electron at the cathode has room to go. They shoot towards the anode, generating an electric current. The higher the voltage, the more electrons move toward the anode per second.

4. 

   
   
   Understand the concept of resistance. Resistor has the nature of its name. The higher the resistance of an object, the harder it is for electrons to pass through it. It slows down the current, because now less electrons can pass through each second.
   • A resistance is anything that belongs to a circuit and adds resistance to a circuit. You can buy a real "resistor" at a power store, but in circuit problems, resistance is usually represented by a light bulb or any other resistive object.

5. 

   Remember Ohm's law. There is a very simple relationship that exists between amperage, voltage and resistance. Write it down or memorize it - you'll have to use it regularly when solving circuit problems:
   • Current = voltage divided by resistor
   • It is usually written in the form: I = / _R
   • Think about what happens when increasing V (voltage) or R (resistance). Does it match what you learned in the explanation above?
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Part 2 of 3: Calculate the voltage of the resistor (series circuit)

1. 

   Understand what a serial circuit is. The serial circuit is easy to identify. It was just a coil, with everything lined up in a row. Current travels around the entire coil, passing in turn through each of the resistors or components that make up the circuit.
   • Amperage the same at every point on the circuit.
   • When calculating the voltage, the position of the resistor in the circuit does not matter. You can take and change the resistor position, the voltage of each resistor will remain the same.
   • Consider an example circuit with three series resistors: R₁, R₂, and R₃. This circuit is powered by a 12V battery. We will find the voltage of each resistor.

2. 

   Calculate the resistance throughout the circuit. Add up all the resistance values ​​in the circuit. The answer is the full circuit resistance of the series circuit.
   • Take for example three resistors R₁, R₂, and R₃ The resistances are 2 Ω (ohms), 3 Ω, and 5 Ω, respectively. The full circuit resistance is 2 + 3 + 5 = 10 ohms.

3. 

   Find the amperage. Use Ohm's law to find the amperage of the entire circuit. Remember that in the series circuit, the amperage is the same at all positions. Once we have computed the line this way, we can use it for all calculations.
   • Ohm's Law says that the amperage I = / _R. The full-circuit voltage is 12 volts, and the full-circuit resistance is 10 ohms. The answer is I = / ₁₀ = 1.2 amp.

4. 

   Transform Ohm's law to find voltage. With basic algebra, we can transform Ohm's law to find voltage instead of amperage:
   • I = / _R
   • IR = R / _R
   • IR = V
   • V = IR

5. 

   Calculate the voltage of each resistor. We already know the value of resistance, we know the amperage, and we already have the equation. Change the number and solve. For the example problem, we have:
   • Repulsion of R₁ = V₁ = (1.2A) (2Ω) = 2.4V.
   • The voltage of R₂ = V₂ = (1.2A) (3Ω) = 3.6V.
   • The voltage of R₃ = V₃ = (1.2A) (5Ω) = 6.0V.

6. 

   Check your answers. In the series circuit, the total voltage across all resistors must be equal to the full circuit voltage. Add up all the voltages you have calculated and see if you get the full circuit voltage. If that doesn't work, go back and find the error.
   • In our example: 2,4 + 3,6 + 6,0 = 12V, which is the full circuit voltage.
   • If the sum of the voltages was slightly lower (say 11.97 instead of 12), you've probably rounded the number somewhere. Your answer is still correct.
   • Remember that voltage measures the difference in charge, or the number of electrons. Imagine you are counting the number of electrons you see as you travel along a circuit. If the count is correct, you will eventually get the total charge in the electrons from start to finish.
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Part 3 of 3: Calculate the voltage of the resistor (parallel circuit)

1. 

   Understand what parallel circuit is. Imagine a wire with one end located on the battery, the other being split into two separate wires. The two wires run parallel to each other, and are then reconnected again before reaching the other end of the battery. If both the left wire and the right line have one resistor, then the two resistors are connected "in parallel".
   • Parallel circuits can have an arbitrary number of wires. This instruction holds true for circuits divided into one hundred wires and then put together.

2. 

   Think about how current flows in the circuit. In a parallel circuit, current flows through all the paths for which it is supplied. It will run through the wire on the left side, pass the resistor on the left, and reach the other end. At the same time, it will also run through the wire on the right, over the right resistor and to the other end. No part of the current flows backwards or forwards through both resistors in parallel.

3. 

   Use full circuit voltage to find the voltage of each resistor. When you know the full circuit voltage, finding the voltage of each resistor will be incredibly easy. Each parallel wire has the same voltage as that of the entire circuit. Assume a circuit with two resistors in parallel is powered by a 6V battery. The voltage of the left resistor will be 6V and the voltage of the right resistor will also be 6V. It doesn't matter how big the resistor value is. To understand why, let's review the serial circuit mentioned above:
   • Remember that in series circuits, the full circuit voltage is always equal to the sum of the voltage for each voltage drop.
   • Think of each current path as a series circuit. The same is true: by adding up the voltage of the entire resistor, you will eventually get the full circuit voltage.
   • Since the current passing through each wire through only one resistor, the voltage of that resistor must be equal to the total voltage.

4. 

   Calculate the amperage of the full circuit. If the problem does not show the full circuit voltage, you will have to complete a few more steps. Start by finding the amount of current flowing through that circuit. In a parallel circuit, the full circuit current is equal to the sum of the current passing through each parallel branch.
   • In mathematical terms: I_total = I₁ + I₂ + I₃...
   • If you find it difficult to understand, imagine a water pipe divided into two. Total runoff is simply the amount of water flowing through each pipe added together.

5. 

   Calculate the resistance throughout the circuit. In parallel circuits, resistors are not as efficient because they only obstruct current flowing through a single wire or turn. In fact, the more turn circuits there are, the easier it is for current to find its way to the other end. To find the full circuit resistance, solve the following equation and find R_total:
   • / _Rtotal = / _R1 + / _R2 + / _R3...
   • Take for example a circuit with 2 ohms and 4 ohms resistors mounted in parallel. / _Rtotal = 1/2 + 1/4 = 3/4 → 1 = (3/4) R_total → R_total = 1 / (3/4) = 4/3 = ~ 1.33 hugs.

6. 

   Find the voltage from the result obtained. Remember, once we find the full circuit voltage, we have also found the voltage of each parallel wire. Use Ohm's Law, find the whole circuit voltage. Eg:
   • Consider a circuit with a line of 5 amp running through. The full circuit resistance is 1.33 ohms.
   • According to Ohm's law, we have: I = V / R, so: V = IR.
   • V = (5A) (1.33Ω) = 6.65V.
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Advice

• If there is a complicated circuit with series resistors and in parallel, or choose two close together resistors. Find their combined resistances using the correct series or parallel resistance rule. At this point, you can think of them as a single resistor. Do this until a simple circuit with resistors is obtained or parallel, or serial.
• The voltage of a resistor is often referred to as a "voltage drop".
• Understand terminology:
  • Circuit - which consists of the parts that make up the circuit (such as resistors, capacitors and inductors) connected by wires and where current can flow in it
  • Resistors - parts that can reduce or interfere with current
  • Electric current - electric charge flowing into the wire, unit: Amp, A
  • Voltage - the work done to move a charged particle; Unit: Volt, V
  • The resistance of an object - a measure of its resistance to the current; Unit: Hug, Ω