I disagree with in Colin in that when one of the diodes open the full wave bridge circuit now becomes a 1/2 wave rectifier. I would expect to see a 50 percent drop in voltage along with a ripple frequency of 60 hertz instead of 120 hertz. I would also expect the output ripple to increase.
for a full wave bridge Vo = .693 Vpeak
1/2 wave rectifier Vo = .318 Vp
One thing to remember though when the output of the rectifier is fed to a capacitor (filter) the average output voltage and ripple will change will change, output voltage Vave will go up and the ripple voltage will go down, but the ripple frequency will remain un-changed.
As for measuring the ripple frequency - need a oscilloscope or a frequency counter ( some DMM have this function).
