What's reading for multimeter set to read dc voltage and bandwidth of 10khz

In summary, the conversation discusses the measurement of noise from a receiver using an RMS voltmeter with a bandwidth of 100kHz. The voltmeter reads 2mV, and the question is posed about what the reading would be for a multimeter set to measure DC voltage with a bandwidth of 10kHz. The answer is determined to be 0.2mV, as the bandwidth is reduced by a factor of 10. The conversation also clarifies the difference between RMS and DC measurements and how they relate to AC signals. The conclusion is that the average value of an AC signal measured on a DC meter will be 0, as explained by the concept of root mean square.
  • #1
chipmunk22
15
0
Happened to come across this qn:

Noise from receiver is measured by rms voltmeter with bandwidth 100khz, and voltmeter reads 2mV. what will be the reading for multimeter set to read dc voltage and bandwidth of 10khz?

My ans is 10/100 x 2 = 0.2mV. cos smaller bandwidth reduced by a factor of 10.

Can anyone comment whether my answer is correct? tks
 
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  • #2
Read the question carefully - in particular, the abbreviations "rms" and "dc".
 
  • #3
so u mean the voltage reading shdnt change? since rms value and dc value are the same.
 
  • #4
RMS and DC are not the same if you are measuring an voltage that varies with time.

A DC meter measure the average (mean) value of an AC signal, which is zero for a symmetrical wave form like a sine wave or a square wave.

Connect a DC voltmeter to a low voltage AC signal generator sometime, and see what reading you get - zero.

The "noise" in the question is basically an AC signal so its average value measured on a DC meter will be 0.

Check out what "root mean square" means, and how it is different from "mean" or "average".
 
  • #5
Oh now i get it. Thanks for the explanation! ;)
 

1. What does "reading for multimeter set to read dc voltage" mean?

Reading for multimeter set to read dc voltage means that the multimeter is set to measure direct current (DC) voltage. This is the type of current that flows in one direction only, such as from a battery or power supply.

2. How do I set my multimeter to read dc voltage?

To set your multimeter to read dc voltage, turn the dial to the V or DCV setting. Make sure the red lead is connected to the positive (+) terminal and the black lead is connected to the negative (-) terminal. Then, touch the leads to the circuit or component you want to measure.

3. What is the difference between dc voltage and ac voltage?

The main difference between dc voltage and ac voltage is the direction of the current flow. As mentioned, dc voltage flows in one direction only, while ac voltage alternates direction at a specific frequency, typically 60 times per second in the United States. AC voltage is commonly used in homes and businesses, while DC voltage is often used in electronic devices and batteries.

4. What is the bandwidth of 10khz mean for a multimeter set to read dc voltage?

The bandwidth of 10khz means that the multimeter is capable of accurately measuring signals with frequencies up to 10,000 hertz (Hz). This is important because if the signal being measured has a frequency higher than the bandwidth of the multimeter, the readings may be inaccurate.

5. Can I use a multimeter set to read dc voltage to measure ac voltage?

No, a multimeter set to read dc voltage is not suitable for measuring ac voltage. You will need a multimeter with an ACV setting to measure ac voltage accurately. Attempting to measure ac voltage with a dc voltage setting can result in incorrect readings and potential damage to the multimeter.

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