Ok, I'm doing an electronics assignment at the moment and we'e just been getting in to first order filters and the like. As a little demo/experiment thing, we were asked to measure the voltage drop across a single variable resistor being powered by a 9V DC supply. We were then told to twist it and see what happened. This resulted in a very sudden jump in the voltage read by the oscilloscope. We then measured the voltage drop over the same variable resistor but in a potential divider circuit. On turning the dial, the rise and fall in voltage is much smoother. Could anyone please explain the reason for this change in behaviour? Thanks in advance.