Solving Kirchoff's Rules Homework: Questions on Dimmer/Normal/On/Off

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In summary, The conversation discusses a question about using Kirchoff's Rules to solve a problem with voltage sources and resistors. The individual is having trouble with certain parts and asked their teacher for help, but did not receive a clear answer. They then ask for clarification on why certain parts would not have voltage or current using Kirchoff's laws and receive a helpful explanation on how to approach the problem without using the laws.
  • #1
Chewy0087
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Homework Statement



kirchoff.jpg


Homework Equations



Kirchoff's Rules

The Attempt at a Solution



hey there!

i'm having trouble with parts of the question above;

for the first two
a: dimmer, b: normal.

however for c & d I'm confused, I did ask my teacher however he wasn't helpful at all, he told me that c would be normal and d would be "off" however I really don't understand why. I think it might be due to kirchhoffs law's however again i find it difficult to understand, could anyone tell me why d wouldn't be on?

i also encounter the same problem with g & h, i guess I'm not sure how to treat it when there's a line between the batteries.

any help would be appreciated
 
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  • #2
I wouldn't use Kirchhoff's laws to solve this problem. I would use the rules for combining resistors and combining voltage sources into series and parallel combinations. It's really a problem to solve by inspection,with no arithmetic. But if you want to solve it with Kircchhoff's laws, write down the equations.
 
  • #3
Can you see that in the second diagram the voltage at a point between the two batteries is the same as that between the two lamps, relative to either end of the two battery string?

So, if you have two places with no voltage between them, you will not get a current to flow if you put a wire between them? And you won't get a lamp to glow either?

In the last diagram, this is the case, too, but since the wire in the middle can't be carrying a current, you can ignore it or just remove it.
 
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  • #4
vk6kro said:
Can you see that in the second diagram the voltage at a point between the two batteries is the same as that between the two lamps, relative to either end of the two battery string?

So, if you have two places with no voltage between them, you will not get a current to flow if you put a wire between them? And you won't get a lamp to glow either?

In the last diagram, this is the case, too, but since the wire in the middle can't be carrying a current, you can ignore it or just remove it.

that's a great explanation, much obliged sir
 

1. What are Kirchoff's Rules?

Kirchoff's Rules are two principles in electrical engineering used to analyze circuits: Kirchoff's Current Law (KCL) and Kirchoff's Voltage Law (KVL). KCL states that the sum of currents entering a node (or junction) in a circuit must equal the sum of currents leaving the node. KVL states that the sum of voltage drops around a closed loop in a circuit must equal the sum of voltage sources.

2. How do I apply Kirchoff's Rules to a circuit with a dimmer switch?

To apply Kirchoff's Rules to a circuit with a dimmer switch, you must first identify the nodes and loops in the circuit. Then, use KCL to determine the current entering and leaving each node and KVL to determine the voltage drops around each loop. The dimmer switch can be treated as a variable resistor, and its value can be adjusted accordingly in the calculations.

3. What is the difference between a normal, on, off, and dimmer switch?

A normal switch simply turns a circuit on and off, allowing current to flow or not. An on switch is another term for a closed switch, meaning it allows current to flow through the circuit. An off switch is another term for an open switch, meaning it blocks current from flowing through the circuit. A dimmer switch is a variable resistor that allows the user to adjust the amount of current flowing through the circuit, thereby controlling the brightness of a light or the speed of a motor.

4. Can Kirchoff's Rules be applied to any circuit?

Yes, Kirchoff's Rules can be applied to any circuit, regardless of its complexity. These rules are fundamental principles in circuit analysis and are used to solve a wide range of electrical engineering problems.

5. What are some common mistakes when applying Kirchoff's Rules?

Some common mistakes when applying Kirchoff's Rules include not properly identifying the nodes and loops in a circuit, not considering the direction of currents and voltage drops, and not using the correct sign conventions for voltage and current. It is important to carefully label and track the direction of currents and voltage drops in a circuit to avoid errors in the calculations.

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