## Circuit Lab B/C

Cathy-TJ
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### Re: Circuit Lab B/C

mjcox2000 wrote:
Cathy-TJ wrote:Calculate the resistance between terminals A and B in the infinite chain of resistors where all resistors are 1 ohm.
Since the network repeats, if its resistance is R, it consists of a 1-ohm resistor in series with a unit consisting of a parallel 1-ohm and R-ohm resistor. Solving for R, we see that $R=\frac{1+\sqrt5}2\Omega$, or assuming sufficient sig figs, about $1.618\Omega$.
Nice!
The answer is also the golden ratio!
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mjcox2000
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### Re: Circuit Lab B/C

Positive and negative charge carriers behave the same in almost all circuits. However, there are some circuits in which it actually makes a difference whether charge carriers are positive or negative. What is an example of a circuit in which this matters, and why does the distinction matter for this circuit?
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Cathy-TJ
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### Re: Circuit Lab B/C

mjcox2000 wrote:Positive and negative charge carriers behave the same in almost all circuits. However, there are some circuits in which it actually makes a difference whether charge carriers are positive or negative. What is an example of a circuit in which this matters, and why does the distinction matter for this circuit?
N-gate and P-gate transistors? P gates allow flow when the signal is low (logic 0), while N-gates allow flow when the signal is high (logic 1).
Might be misinterpreting this question.
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mjcox2000
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### Re: Circuit Lab B/C

Cathy-TJ wrote:
mjcox2000 wrote:Positive and negative charge carriers behave the same in almost all circuits. However, there are some circuits in which it actually makes a difference whether charge carriers are positive or negative. What is an example of a circuit in which this matters, and why does the distinction matter for this circuit?
N-gate and P-gate transistors? P gates allow flow when the signal is low (logic 0), while N-gates allow flow when the signal is high (logic 1).
Might be misinterpreting this question.
That’s not what I was going for.

Let me try rephrasing the question: Describe a circuit in which macro-level measurements of the circuit would differ depending on whether charge carriers are electrons flowing opposite conventional current or positive charge carriers flowing in the direction of conventional current.
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Cathy-TJ
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### Re: Circuit Lab B/C

mjcox2000 wrote:
Cathy-TJ wrote:
mjcox2000 wrote:Positive and negative charge carriers behave the same in almost all circuits. However, there are some circuits in which it actually makes a difference whether charge carriers are positive or negative. What is an example of a circuit in which this matters, and why does the distinction matter for this circuit?
N-gate and P-gate transistors? P gates allow flow when the signal is low (logic 0), while N-gates allow flow when the signal is high (logic 1).
Might be misinterpreting this question.
That’s not what I was going for.

Let me try rephrasing the question: Describe a circuit in which macro-level measurements of the circuit would differ depending on whether charge carriers are electrons flowing opposite conventional current or positive charge carriers flowing in the direction of conventional current.
A circuit that uses Hall effect, since changing the charge carrier would reverse the voltage produced.
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mjcox2000
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### Re: Circuit Lab B/C

Cathy-TJ wrote:
mjcox2000 wrote:
Cathy-TJ wrote:
N-gate and P-gate transistors? P gates allow flow when the signal is low (logic 0), while N-gates allow flow when the signal is high (logic 1).
Might be misinterpreting this question.
That’s not what I was going for.

Let me try rephrasing the question: Describe a circuit in which macro-level measurements of the circuit would differ depending on whether charge carriers are electrons flowing opposite conventional current or positive charge carriers flowing in the direction of conventional current.
A circuit that uses Hall effect, since changing the charge carrier would reverse the voltage produced.
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Cathy-TJ
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### Re: Circuit Lab B/C

When and why would you use a Kelvin Double Bridge?
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### Re: Circuit Lab B/C

To measure unknown resistors under 1 Ohm?
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Cathy-TJ
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### Re: Circuit Lab B/C

Things2do wrote:To measure unknown resistors under 1 Ohm?
That's right!
the resistance of the wires becomes significant
You have the next question!
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### Re: Circuit Lab B/C

Since no one has posted a question yet:

An LED with voltage drop $3.2V$ and internal resistance $2\Omega$ is in series with a voltage $V$ and resistance $R$. The LED’s maximum rated current is $10mA$, and the minimum current at which its light is visible is $100\mu A$.

1. What is the minimum series voltage $V$ for the LED to emit visible light?
2. Given the value of $V$, write equations for the minimum and maximum value of $R$ for the LED to emit visible light without burning out.
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