ClassX Video Lessons Youtube Channel The Engineering Mindset DC Series circuits explained – The basics working principle
Welcome to an exploration of DC series circuits, where we delve into the fundamentals of voltage, current, resistance, and power consumption. This guide will also introduce you to the use of a multimeter, providing a practical approach to understanding these concepts.
In electrical engineering, components can be connected in series, parallel, or a combination of both. This guide focuses on series circuits, the simplest form of connection. In a series circuit, components are connected end-to-end, providing a single path for electron flow. This flow is often described using electron flow (negative to positive), although conventional current (positive to negative) is also commonly taught.
Resistance, measured in ohms, is a property of components that opposes the applied voltage. In a series circuit, the total resistance is the sum of individual resistances. For example, if a circuit contains a 10-ohm resistor (R1) and a 5-ohm resistor (R2), the total resistance is 15 ohms. This cumulative resistance affects the overall current flow in the circuit.
Current, the flow of electrons, is measured in amperes (amps). In a series circuit, the current is consistent throughout. To measure current, an ammeter is placed within the circuit. The total current can be calculated by dividing the voltage by the total resistance. For instance, a 9-volt battery with a total resistance of 15 ohms results in a current of 0.6 amps (9 volts / 15 ohms).
Voltage, akin to pressure in a water pipe, is the force that pushes electrons through a circuit. In a series circuit, voltage is divided among the components. For example, with a 9-volt battery and two resistors (10 ohms and 5 ohms), the voltage drop across the 10-ohm resistor is 6 volts, and across the 5-ohm resistor, it is 3 volts. The sum of these voltage drops equals the total voltage supplied by the battery.
Power, measured in watts, can be calculated using the formula: Power = Voltage x Current or Power = Voltage² / Resistance. In a series circuit with a 9-volt battery and a 10-ohm resistor, the power consumed is 8.1 watts (9 volts x 0.9 amps). This power is dissipated as heat, which can be observed using thermal imaging.
Understanding these principles is crucial for designing and troubleshooting circuits. For instance, if an LED with a maximum current rating of 0.02 amps is connected to a 9-volt battery, selecting the appropriate resistor is essential to prevent damage. Calculating the current with different resistors helps ensure the LED operates safely.
To further your learning, consider experimenting with a multimeter to measure voltage, current, and resistance in various circuits. This hands-on approach will reinforce the concepts discussed and enhance your practical skills.
Thank you for exploring DC series circuits with us. For more in-depth tutorials, visit our website and follow us on social media. Continue your journey into the world of electrical engineering with our additional resources and videos.
Gather basic components such as resistors, a battery, and wires. Assemble them into a series circuit. Use a multimeter to measure the voltage across each component and the total current in the circuit. This hands-on activity will help you understand how voltage and current behave in series circuits.
Calculate the total resistance of a series circuit with various resistor values. Use different combinations and verify your calculations by measuring with a multimeter. This exercise will reinforce your understanding of how resistances add up in series circuits.
Set up a series circuit with multiple resistors and a power source. Measure the voltage drop across each resistor using a multimeter. Compare your measurements with theoretical calculations to see how voltage is divided among components in a series circuit.
Calculate the power consumed by each component in a series circuit using the formula Power = Voltage x Current. Verify your calculations by measuring the actual power consumption with a multimeter. This activity will deepen your understanding of power distribution in circuits.
Design a series circuit that includes an LED and a resistor. Calculate the appropriate resistor value to ensure the LED operates safely without exceeding its maximum current rating. Test your design by building the circuit and measuring the current with a multimeter.
**Sanitized Transcript:**
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**[Instructor]** Hey there, everyone! Paul here from the engineering mindset. In this video, we’re going to explore DC series circuits. We’ll cover voltage, current, resistance, and power consumption, as well as using a multimeter, with a chance for you to test your knowledge at the end.
When we connect components in an electrical circuit, we can connect them either in series or parallel, or we can combine these to create a series-parallel circuit. We’ll start with the series type, which is the most basic. We will cover the other types in future tutorials, so be sure to check those out via the links below.
In a series connection, if we place two components end to end, or with some wires in between, they are connected in series. The electrons have only one path to take, so they flow through each of the components. In these animations, I use electron flow, which is from negative to positive. You might be familiar with conventional current, which is from positive to negative. Electron flow is what actually occurs, while conventional current is the original theory that is still taught for simplicity. Just be aware of the two and which one we’re using.
**Resistance in Series Circuits:** Each component has a certain resistance that opposes the voltage being applied. We measure resistance in ohms. In series circuits, we find the total resistance by adding together all resistances. We label each resistor with a capital R and number them R1, R2, R3, etc. The total resistance is shown with a capital R and a subscript T, indicating the total resistance.
Calculating the total resistance of a series circuit is straightforward. For example, if we have a circuit with a single resistor, R1, with a value of 10 ohms, the total resistance is simply 10 ohms. If we then add a second resistor, R2, with a resistance of 5 ohms, the total resistance becomes 15 ohms (10 ohms + 5 ohms). If we add another 5-ohm resistor, the total resistance is now 20 ohms. In reality, the wires will also add some resistance, but this is usually negligible unless high accuracy is required.
**Current in Series:** Current is the flow of electrons, similar to water flowing through a pipe. The higher the current, the more electrons are flowing. We measure current in Amperes, often shortened to amps. We measure current by placing an ammeter in the circuit for the electrons to flow through, similar to a water meter.
To measure current with a multimeter, it must be placed in the circuit. The meter will add some resistance, but it’s usually small enough to ignore. If you don’t have a multimeter yet, I highly recommend getting one, as they are essential for troubleshooting and enhancing your understanding.
We can calculate the total current of the circuit by dividing the voltage by the resistance. For example, if we connect a 10-ohm resistor to a 9-volt battery, 9 volts divided by 10 ohms gives us 0.9 amps. If we add another 5-ohm resistor, the total resistance becomes 15 ohms, so 9 volts divided by 15 ohms equals 0.6 amps. Adding another 5-ohm resistor results in a total resistance of 20 ohms, leading to 9 volts divided by 20 ohms equaling 0.45 amps. This shows that as we add more resistance, the current decreases, meaning fewer electrons are flowing, which reduces the work that can be done.
We can visualize this by connecting an LED with a resistor in a circuit. The higher the resistance, the dimmer the LED will be. Resistors can also protect components in the circuit. For instance, using a 100-ohm resistor with a 9-volt battery results in a current of around 0.09 amps (90 milliamps), which could damage the LED. A 450-ohm resistor would yield around 0.02 amps (20 milliamps), which should be safe for the LED. A 900-ohm resistor would result in a current of 0.01 amps (10 milliamps), making the LED very dim.
In a series circuit, the current is the same throughout the entire circuit. This is important to remember. If we measure the current at different points, we will get the same reading, as there is only one path for the electrons to flow.
**Voltage in Series:** Voltage is the pushing force of electrons, similar to pressure in a pipe. The higher the voltage, the more electrons can flow. We can see this by varying the voltage to a lamp; the lamp increases in brightness as the voltage increases.
When measuring voltage, we measure the difference between two points. For example, across a 1.5-volt battery, we get a reading of 1.5 volts. However, measuring the same side won’t yield any voltage; we can only measure the difference between two points.
If we place a 9-volt battery into the circuit, we apply 9 volts. We can increase this by wiring batteries in series. For instance, two 9-volt batteries in series yield 18 volts, while three give us 27 volts.
Let’s take a 9-volt battery and add a 10-ohm resistor (R1) to the circuit. Measuring across the resistor gives us a voltage reading of 9 volts. Adding another 10-ohm resistor results in a reading of 9 volts across both resistors, but measuring across either resistor individually gives us 4.5 volts. The resistors divide the voltage.
If we replace the second resistor (R2) with a 5-ohm resistor, the total voltage remains 9 volts. Measuring across the two resistors shows 9 volts, but measuring across the 10-ohm resistor gives us 6 volts, and across the 5-ohm resistor, we see 3 volts.
Adding another 5-ohm resistor (R3) results in a total voltage drop of 9 volts across the three resistors. Across R1 (10 ohms), we read 4.5 volts; across R2 and R3 (5 ohms each), we read 2.25 volts each.
We can combine these readings to find the voltage at different parts of the circuit. For example, measuring from the battery across R1 gives us 4.5 volts. Measuring from the battery across R1 and R2 gives us 6.75 volts (4.5 + 2.25 volts).
Unlike current, which is the same throughout the circuit, voltage varies in a series circuit. Each resistor creates a voltage drop, which is its purpose: to reduce the voltage or pressure. The resistor creates a more difficult path for the electrons, causing collisions that convert energy into heat. The same number of electrons enter and exit the resistor, but they have less energy due to the voltage drop.
We can calculate the voltage drop across each resistor individually by multiplying the total current in the circuit by the resistance of each component. Remember, in a series circuit, the current is the same everywhere.
The total voltage drop is the sum of all individual voltage drops. In the first circuit with a 10-ohm resistor, the current was 0.9 amps, so 0.9 amps multiplied by 10 ohms equals 9 volts.
In the second circuit with a 10-ohm and a 5-ohm resistor, the first resistor’s voltage drop is 0.6 amps multiplied by 10 ohms, giving us 6 volts. The second resistor’s voltage drop is 0.6 amps multiplied by 5 ohms, resulting in 3 volts. The total voltage drop is 6 volts + 3 volts = 9 volts.
In the third circuit with a 10-ohm and two 5-ohm resistors, the current was 0.45 amps. R1’s voltage drop is 0.45 amps multiplied by 10 ohms, giving us 4.5 volts. R2 and R3’s voltage drops are 0.45 amps multiplied by 5 ohms, resulting in 2.25 volts each. The total voltage drop is 9 volts (4.5 + 2.25 + 2.25).
**Power Consumption in Series Circuits:** To measure power consumption, we can use the following equations: Power (in watts) equals voltage squared divided by resistance, or power equals voltage multiplied by current.
You might wonder how a resistor consumes power. As the resistor creates a voltage drop, the electrons lose energy, which is converted into heat. If we look at resistors with a thermal imaging camera, we can see the heat generated.
In a circuit with a 10-ohm resistor and a 9-volt battery, the current is 0.9 amps, and the circuit consumes 8.1 watts of power. We calculate this using the first method: 9 volts squared (81) divided by 10 ohms equals 8.1 watts. Alternatively, 9 volts multiplied by 0.9 amps also equals 8.1 watts.
In the circuit with a 10-ohm and a 5-ohm resistor, the total resistance is 15 ohms, and the current is 0.6 amps. Using the first method, 9 volts squared (81) divided by 15 ohms equals 5.4 watts, or 9 volts multiplied by 0.6 amps equals 5.4 watts.
In the circuit with a 10-ohm and two 5-ohm resistors, the total resistance is 20 ohms, and the current is 0.45 amps. Using the first method, 9 volts squared (81) divided by 20 ohms gives us 4.05 watts, or alternatively, 9 volts multiplied by 0.45 amps equals 4.05 watts.
Now it’s time for you to test your knowledge. This LED can’t exceed a maximum current of 0.02 amps (20 milliamps), or it will burn out. If we connect it to these resistors and a 9-volt battery, what will the approximate current in the circuit be? I’ll leave a link in the video description for the answer.
That’s it for this video! To continue your learning, check out one of the videos on screen now, and I’ll catch you in the next lesson. Don’t forget to follow us on social media and visit the engineering mindset website.
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This sanitized version removes informal language and maintains a professional tone while preserving the educational content.
dc – Direct current, a type of electrical current that flows consistently in one direction. – In many electronic devices, dc is preferred over alternating current because it provides a constant voltage level.
series – A configuration of electrical components connected end-to-end so that the same current flows through each component. – When resistors are connected in series, the total resistance is the sum of the individual resistances.
circuits – Electrical networks consisting of a closed loop, giving a return path for the current. – Understanding how circuits work is fundamental to designing any electronic device.
resistance – A measure of the opposition to the flow of current in an electrical circuit. – The resistance of a material determines how much current will flow for a given voltage.
current – The flow of electric charge in a conductor, typically measured in amperes. – The current flowing through the circuit was measured to be 5 amperes.
voltage – The electric potential difference between two points, which drives current through a circuit. – The voltage across the battery terminals was measured to be 12 volts.
power – The rate at which electrical energy is transferred by an electric circuit, typically measured in watts. – The power consumed by the resistor was calculated using the formula P = IV.
engineering – The application of scientific and mathematical principles to design and build structures, machines, and systems. – Engineering students often work on projects that require both creativity and technical knowledge.
multimeter – An instrument used to measure voltage, current, and resistance in electrical circuits. – The multimeter was used to diagnose the fault in the circuit by measuring the voltage drop across components.
electrons – Subatomic particles with a negative charge, which flow through conductors to create electric current. – In a conductor, electrons move from the negative terminal to the positive terminal, creating an electric current.
