Low Pass: Why did my professor use frequency and not angular frequency?

In summary, the conversation discusses a problem involving a passive RC low pass filter with specific values for the resistor and capacitor. The task is to calculate the magnitude and phase angle of the output voltage. The equations used are UR = R*I, Uout = I*XC, XC = I / ω*C, and ω = 2*π*f. However, there is confusion over the value of ω, as the professor used the frequency f instead of 2πf in the solution provided. This is believed to be a clerical error.
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space5678
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Homework Statement



We are given a passive RC low pass filter with an input voltage of 5 Vrms at a frequency of 1 kHz. The resistor has a value of 22 kΩ, the capacitor a value of 100 nF. There is a current i across the resistor. (see picture below)

We are to calculate the magnitude and phase angle of the output voltage.

By the way, in the picture below is in german, so V eff means rms, I think the rest should be apparent.

94AFb9GrvH3MXwQBm89aUlN8Y3uIzISAg6c_f-yAIpamzl6iDAXYupibtgi9B1d-wFy2QfeLmwWCXhTYH0=w1142-h816-no.jpg


Homework Equations



UR = R*I

Uout = I*XC

XC = I / ω*C

ω = 2*π*f (in rad/s)

The Attempt at a Solution



Analytically, this is not a problem, and I have attached the solution from the professor. My only problem is that for ω the professor used the frequency f, and not 2πf. As in:

ω = f = 1 kHz

This makes no sense to me and seems wrong. Could somebody possibly clarify what´s going on here? Thanks in advance.
 
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  • #2
Seems wrong to me as well. I got 0.36V.
 
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  • #3
CWatters said:
Seems wrong to me as well. I got 0.36V.

I think this must be a clerical mistake, as in all of the other examples he uses ω = 2πf. Thanks a bunch for checking! :oldsmile:
 

1. Why is frequency used instead of angular frequency in low pass filters?

Frequency is used because it is a more intuitive and commonly used unit of measurement for oscillatory motion. It is also easier to interpret in terms of the cutoff frequency, which is the point at which the filter begins to attenuate signals.

2. Can angular frequency be converted to frequency in low pass filters?

Yes, angular frequency (ω) and frequency (f) are related by the equation ω = 2πf. Therefore, they can be easily converted from one unit to the other.

3. What is the significance of using frequency in low pass filters?

Frequency is used in low pass filters to determine the range of frequencies that the filter will allow to pass through. This is important in signal processing and communication systems, as it allows for the selective filtering of specific frequency components.

4. Are there any advantages to using angular frequency instead of frequency in low pass filters?

In some cases, using angular frequency can make the mathematical equations and calculations simpler and more concise. However, in terms of practical applications and understanding, frequency is the more commonly used unit.

5. What are some other applications of using frequency in science and engineering?

Frequency is used in a wide range of fields, including physics, engineering, and biology. It is used in the analysis of periodic motion, electromagnetic waves, and electrical circuits, among others. It also plays a crucial role in fields such as acoustics, optics, and spectroscopy.

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