Calculating Cutoff Frequency with Oscilloscope and Coaxial Cable

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Homework Help Overview

The discussion revolves around calculating the cutoff frequency using an oscilloscope and a coaxial cable, focusing on the impedance of both components and their configuration. The original poster presents specific values for the oscilloscope and coaxial cable, seeking clarification on how to interpret their arrangement in relation to each other.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to understand the relationship between the oscilloscope's impedance and the coaxial cable's impedance, questioning whether they are in series or parallel. Participants explore the physical characteristics of capacitors and coaxial cables to inform their reasoning.

Discussion Status

Some participants have offered hints to guide the original poster's understanding of capacitors and coaxial cables, prompting further exploration of the problem. The discussion is ongoing, with multiple interpretations of the circuit configuration being considered.

Contextual Notes

The original poster expresses uncertainty about the arrangement of components and how this affects the calculation of the cutoff frequency. There is an attachment referenced that may provide additional context, but its content is not detailed in the discussion.

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First take a look at the attachment (See reply below). We have to take the oscilloscope's impedance and the coaxial cable's impedance into account. And then we have to calculate the cutoff frequency of this.
Given: Oscilloscope: R=1M Ohm // C=25pF
Coaxial Cable: R=75 Ohm and C=68pF/m with L=0.85m
C=57.8pF

My problem is that I don't know how to draw this. R and C from the Coaxial cable, are they serial or parallel? And the coaxial cable's impedance is that serial or parallel to the oscilloscope's impedance?

If I know that, I can calculate the cutoff frequency and the voltages with different frequencies, but now I'm stuck. Thanks in advance.
 
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Attachment

And here's the attachment :).
 

Attachments

  • cutofffreq.jpg
    cutofffreq.jpg
    8.9 KB · Views: 436
Anyone? Or is my question not clear enough?
 
Here's a hint: What is a capacitor? In asking this I'm prodding you into thinking about how a capicitor is physically made from there you should be able to figure out the problem. Also, do you know what a coaxial cable is and how it is constructed? If you don't know google it. If you do know, think about the construction of the coax cable and that of a capacitor. Good Luck
 
Well a capacitor is actually two charged conductors very close to each other, so there's a voltage difference between them, right? And a coaxial Cable has an inner and an outer conductor, so those two conductors are responsible for the capacitance. That means the capacitance has to be parallel, right?

SO it has to be one of this two schemes (attached)?
Only I'm not sure which one...
 

Attachments

  • cutoffreq2.jpg
    cutoffreq2.jpg
    10 KB · Views: 448

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