Does Ohm's Law Apply to a Circuit with Current but No Voltage?

In summary: For example, the logarithm function is undefined at zero or negative numbers.In summary, the conversation discusses the application of Ohm's law in a circuit with two resistors and the presence of current. It is explained that Ohm's law still applies, but in the ideal case, there is no voltage drop between two points on a wire, leading to an indeterminate form of 0/0. The difference between indeterminate and undefined is also explained, with indeterminate being used in the context of limits and undefined referring to numbers not in a function's domain.
  • #1
FS98
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4
in a circuit like the one in the attached picture, the voltage between two points in between two resistors should be 0.

But there is current flowing through the circuit.

So what’s going on here? Does ohms law not apply in this situation for some reason?
 

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  • #2
Add the two points where you are taking measurements to the schematic.
 
  • #3
Ohm's law still applies. In the idealized case, the connecting wires between the resistors have zero resistance thus essentially zero voltage drop is required to produce a current. In reality, there is some resistance and thus some small voltage drop between two adjacent points on the conducting wires.

(Assuming I understand your question.)
 
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  • #4
One does not normally apply Ohms Law to an ideal wire because you get what I assume is confusing you which is V=IR leading to 0 = I*0 or I = 0/0 and the problem w/ that is that 0/0 is undefined.
 
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  • #5
0/0 is indeterminate.
 
  • #6
cabraham said:
0/0 is indeterminate.
In the context of a limit, 0/0 is an "indeterminate form". That is if one has two functions, f() and g() and if ##\lim_{x \to c}f(x) = 0## and ##\lim_{x \to c}g(x) = 0## then one cannot determine from that information alone whether ##\lim_{x \to c} \frac{f(x)}{g(x)}## exists or, if it does, what value it takes.

As a standalone formula, ##\frac{0}{0}## is simply undefined.
 
  • #7
cabraham said:
0/0 is indeterminate.
What's the difference between indeterminate and undefined?
 
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  • #8
phinds said:
What's the difference between indeterminate and undefined?
"Indeterminate" is used in the context of limits, as @jbriggs444 already said, and means that some work is required to determine whether they represent numbers. Some indeterminate forms are ##[\frac 0 0]##, ##[\frac \infty \infty]##, ##[\infty - \infty]##, and ##[1^\infty]##. Most textbooks write these forms in brackets to emphasize that they are "forms" rather than actual numbers.
The following limits are examples of the first three types I listed:
##\lim_{x \to 1}\frac{x^2 - 1}{x - 1}##
##\lim_{t \to \infty}\frac{t^2 + 2}{t^3 - 1}##
##\lim_{y \to \infty}y^2 - y^3##
These are called indeterminate forms because it's not obvious at first glance that they represent a number. By taking a limit and subsequent algebraic or other operations, one can determine that a limit actually exists or not.

As for undefined -- the division of any number by zero is undefined, as is taking the square root (or fourth root or any even root) of a negative number is undefined (if we're dealing with the real-valued square root function). In general, attempting to evaluate a function at a number not in its domain is undefined.
 
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1. What is "current without voltage"?

"Current without voltage" refers to the flow of electrical current in a circuit without any voltage being applied. This can occur in a closed circuit with a constant current source or in a circuit with only capacitive or inductive components.

2. How is current without voltage measured?

Current without voltage can be measured using an ammeter, which measures the flow of electrical current in a circuit. The ammeter should be placed in series with the circuit to accurately measure the current.

3. What causes current without voltage?

Current without voltage is caused by the presence of inductors and capacitors in a circuit. These components can store and release energy, creating a flow of current even without a voltage source.

4. Is current without voltage useful?

Yes, current without voltage can be useful in certain applications. For example, inductors and capacitors are commonly used in electronic circuits to filter out certain frequencies and regulate the flow of current.

5. How does current without voltage affect power consumption?

In circuits with only inductive or capacitive components, current without voltage can result in reactive power consumption. This means that the current is not being used to do any work, but is instead being stored and released by the components. This can affect the overall efficiency of the circuit and may require additional measures to correct for this reactive power consumption.

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