Sources in Series and Parallel (Circuits for Beginners #10)

Summary

This video explains electrical circuits using analogies to mechanical potential energy and gravity. It discusses how voltage behaves in series and parallel configurations, highlighting how voltages add in series but remain the same in parallel. The video explores the practical reasons for wiring voltage sources and current sources in various ways, such as reducing the load on individual sources or managing unequal voltages. It also covers the challenges and considerations when connecting real batteries or current sources in parallel, especially when their voltages or currents are different, demonstrating potential risks like draining batteries or creating instability in the circuit.

Takeaways

• 😀 Voltage represents electric potential, similar to mechanical potential energy in a gravity well.
• 😀 It takes work to push electrons through voltage sources, much like a person expending energy to climb a hill.
• 😀 Voltage sources in series add up like heights in a gravitational potential energy scenario (e.g., 6V + 10V = 16V).
• 😀 Voltage sources in parallel do not add their voltages, instead, the voltage stays the same as one of the sources.
• 😀 Wiring voltage sources in parallel can help balance the current load, as each source supplies only part of the current.
• 😀 When connecting two batteries with different voltages in parallel, the higher voltage battery will charge the lower one, leading to an intermediate voltage.
• 😀 Combining old and new batteries in parallel can drain the new battery as it charges the old one, which is inefficient and not recommended.
• 😀 Current sources in parallel add their currents (e.g., a 2A and 1A current source combine to provide 3A).
• 😀 Current sources in series do not add their currents; instead, the current is determined by the lowest current source in the series.
• 😀 In a series arrangement of current sources, each source provides less power, as the voltage drop across each is shared between them.
• 😀 Combining imperfect current sources in series leads to an intermediate current, and in parallel, stronger sources may end up charging weaker ones.
• 😀 Real-world scenarios with non-ideal voltage and current sources require careful consideration to avoid inefficient power transfer or battery damage.

Q & A

What is voltage, and how is it related to electric potential?

Voltage represents electric potential, which is a measure of the potential energy per unit charge in an electrical circuit. It's similar to mechanical potential energy, like gravity in a gravitational field.

How can voltage be compared to mechanical potential energy?

Voltage is analogous to mechanical potential energy, like the energy a person would need to climb a hill. Just as it takes work to climb a hill, it takes work to move charges through a voltage source.

How do voltage sources in series behave, and what happens to their voltages?

When voltage sources are connected in series, their voltages add up. For example, if you have two batteries with different voltages, their total voltage will be the sum of their individual voltages, like how the height of two hills adds together.

Why do we sometimes wire voltage sources in parallel, and what effect does this have?

Voltage sources in parallel are wired when you need to reduce the current each source supplies. The voltage across both sources remains the same, but the current is divided between them, allowing each source to share the load.

What is the result of connecting voltage sources with different voltages in parallel?

When you connect voltage sources with different voltages in parallel, the stronger source will charge the weaker one. The resulting voltage across both sources will be somewhere between the two original voltages.

Why is it not recommended to connect old and new batteries in parallel?

Connecting old and new batteries in parallel is not recommended because the old battery will drain the new battery as it tries to charge the weaker one. This wastes energy and could damage the batteries.

What happens when current sources are combined in parallel?

When current sources are connected in parallel, their currents add up. For example, if one source provides 2 amperes and another provides 1 ampere, the total current is 3 amperes.

How do current sources behave when connected in series?

Current sources connected in series do not add their currents. Instead, the same current flows through all sources. If two sources are connected in series, they both carry the same current, but the voltage across them adds up.

What is the advantage of connecting current sources in series?

By connecting current sources in series, you can reduce the power each source has to supply. For example, two 1-ampere sources in series would each only need to supply half of the total power.

What happens when current sources with different currents are connected in series?

Connecting current sources with different current ratings in series is a mathematical impossibility, as a wire can only carry one current. The system would not work because it's impossible to define two different currents through the same wire.