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Today, we'll explore parallel circuits! In a parallel circuit, the voltage across each branch is the same. Who can tell me why that might be important?
Because each device can operate independently?
Exactly! That's why if one branch fails, others can still function. Can anyone tell me how we calculate total current in a parallel circuit?
I think we add up the currents in each branch?
Correct! Total current I_total equals the sum of the currents in each branch. To visualize it, think of water flowing through multiple hoses. The more hoses you add, the more total water flows.
So if we add more branches, current increases?
Yes! That's how we'll structure our investigation with 220 ฮฉ resistors today.
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Let's start our investigation! We will connect a 9V supply and one 220 ฮฉ branch first. What will happen to total current?
I think we calculate I using Ohm's law, V = I ร R!
Correct! Letโs calculate it. Whatโs the current with just one branch?
The current will be 9V / 220ฮฉ, which is around 0.04 A.
Great! Now, what do you think will happen if we add another 220 ฮฉ branch?
The total current will increase, right?
Yes! Letโs keep track of our totals and calculate the new equivalent resistance.
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Now that we've added three branches, let's summarize our data. What did we find for total current with 3 resistors added?
It was somewhere around 0.12 A!
Exactly! And what about our equivalent resistance?
I think we can calculate it as R_eq = 220ฮฉ / 3.
Right! That gives us 73.3 ฮฉ. This shows how parallel circuits can provide lower resistance than individual resistors. Can anyone think of a real-life application?
Like in household wiring where multiple devices run at the same time?
Precisely! Excellent work, team.
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In this section, students learn to investigate parallel circuits, observing how the addition of branches influences total current and resistance. By engaging in practical procedures with a 9V power supply and 220 ฮฉ resistors, students gain insights into the relationships between current, voltage, and resistance.
This section delves into the properties of parallel circuits, where components share the same voltage but have multiple pathways for current. The aim is to observe how adding branches impacts total current and the equivalent resistance of the circuit. Students will engage in hands-on activities using a 9V power supply, incrementally adding 220 ฮฉ resistors to analyze the change in total current.
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Aim: Observe impact of branch addition.
The goal of the investigation is to understand how adding more branches to a parallel circuit affects the total current flowing through the circuit. It looks to demonstrate the relationship between the number of branches and the overall current.
Think of a parallel circuit like a multi-lane highway. Each lane can be seen as a branch in the circuit. The more lanes (or branches) you add, the more cars (or current) can travel. Just like adding more lanes reduces traffic congestion, adding more branches permits more current to flow.
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Procedure:
โ Use 9 V supply, add 220 ฮฉ branches one by one.
โ Record I_total for 1 to 4 branches.
In this experiment, a 9 V power supply is used, and branches with a resistance of 220 ฮฉ are added incrementally. The total current flowing from the power supply is recorded for each configuration, from one branch to four branches. This systematic addition of branches will allow us to collect data on how the current changes as the number of branches increases.
Imagine youโre filling multiple buckets with water from a single hose. If you only use one bucket, it fills slowly. But if you add more buckets, each receiving water, the total flow increases, just like adding more branches in a circuit increases total current.
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Calculations:
โ For n branches: I_n = nร(9/220).
โ Compare to measured; compute R_eq = 220/n; discuss discrepancies.
The formula I_n = nร(9/220) calculates the theoretical current for 'n' branches in the circuit, based on the resistance of each branch. By measuring the actual current, students can compare it with the theoretical calculation to see how closely they align. The equivalent resistance is computed as R_eq = 220/n, meaning the total resistance decreases with more parallel branches. Any differences between the expected and actual current can lead to discussions about real-world factors that may affect measurements, like resistance in wires.
Going back to the water buckets, if you expected each bucket to fill at the same rate but found some buckets didn't fill as quickly due to leaks or obstructions, thatโs similar to observing discrepancies in current in a circuit. It reinforces understanding that real-world applications can introduce unexpected variables.
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Key Concepts
In parallel configurations, the voltage across each component remains constant.
Total current in the circuit increases as additional branches are added, as per the equations:
For n branches: I_n = n ร (9V / 220 ฮฉ).
The equivalent resistance can be calculated as R_eq = 220/n.
The section emphasizes practical skills in measurement and the significance of understanding how parallel circuits operate in real-world applications.
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When one branch of a parallel circuit containing three 220 ฮฉ resistors is removed, the other branches continue to operate because they share the same voltage.
In a household circuit, lights and outlets are often arranged in parallel to ensure that each device gets the same voltage supply, even if others are turned off.
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In a parallel strand, voltage stays grand, each branch flows strong, thatโs how we get along!
Imagine a tree with many branches; as you water the tree, every branch gets its fill. Adding branches means more water flows while each still gets what it needs.
P = Potential stays the same; P = Power grows, what a game! \n (P for Potential Voltage, leads to more Power as branches grow.)
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Review the Definitions for terms.
Term: Parallel Circuit
Definition:
A circuit in which components are connected across common points, allowing multiple pathways for current.
Term: Equivalent Resistance (R_eq)
Definition:
The total resistance of the circuit when considering multiple parallel resistors.
Term: Total Current (I_total)
Definition:
The sum of the currents flowing through all branches in a parallel circuit.