oh thanks for replying! this is actually an assignment which I have to submit by tomorrow. There are no provied component values or any other things like that. Just a single question. I can't find out because previously I was just into finding this out with the oscilloscope!
Can you tell me what values should be known, and any relation (formula) which can be used to measure the ripple?
Not all meters (particularly old ones) will block the DC component.
If you use a low-leakage capacitor on one of the test probes, it will block the DC component, but pass the effects of the AC component. If the ripple is a pure sine wave, then the AC scale of a true RMS meter will give you the RMS (average) voltage, and the peak-peak voltage will be the RMS reading multiplied by 1.414 (not exact, but close.) If the ripple is other than a pure sine wave, the RMS reading will be off depending on how distorted the sine wave is.
a multimeter will measure the ac component of a signal as mrmeval explained, with a few exceptions:
1. an ac meter (multimeter) will "read" the rms value (not average)
2. the meter is designed to read 60 hz, so anything else will provide error. you can go to "freq" if the meter has that function and read the frequency
3. anything other then pure sine wave will also provide error