IPhO 1968, Теория и експеримент — Задача 4. Experimental problem
Problems of the 2nd International Physics Olympiads (Budapest, Hungary, 1968)
Условие
Three closed boxes (black boxes) with two plug sockets on each are present for investigation. The participants have to find out, without opening the boxes, what kind of elements are in them and measure their characteristic properties. AC and DC meters (their internal resistance and accuracy are given) and AC (5O Hz) and DC sources are put at the participants’ disposal.
Отговори
- One box contains a simple resistor, one a capacitor, and the third a resistor and an inductor connected in series.
Решение
No voltage is observed at any of the plug sockets therefore none of the boxes contains a source.
Measuring the resistances using first AC then DC, one of the boxes gives the same result. Conclusion: the box contains a simple resistor. Its resistance is determined by measurement.
One of the boxes has a very great resistance for DC but conducts AC well. It contains a capacitor, the value can be computed as .
The third box conducts both AC and DC, its resistance for AC is greater. It contains a resistor and an inductor connected in series. The values of the resistance and the inductance can be computed from the measurements.
Оригинал в Архива: ipho68.pdf