Question
A form of “sensing” based on measuring changes in this quantity is used in proximity sensors, liquid level sensors, and theremins. For 10 points each:
[10m] Phone touchscreens work by measuring localized increases in what quantity where your finger touches the screen?
ANSWER: capacitance [accept capacitive sensing; prompt on C]
[10e] In capacitive sensors, changes in capacitance can be detected by measuring charging times or changes in this quantity for a downstream oscillator, since it equals one over root-LC. For US power systems, this quantity's standard operating value is 60 hertz.
ANSWER: frequency [or angular frequency; accept AC frequency]
[10h] Capacitance changes can also be measured by circuits with this topology. In a circuit with this topology, four resistors are arranged in a square, and connected with a voltmeter between diagonal nodes.
ANSWER: bridge circuits [accept Wheatstone bridges; prompt on lattice circuits]
<VD, Physics>
Summary
| 2024 ARCADIA at Waterloo | 2024-11-09 | Y | 6 | 11.67 | 100% | 17% | 0% |
| 2024 ARCADIA at Illinois | 2024-11-09 | Y | 4 | 20.00 | 100% | 25% | 75% |
| 2024 ARCADIA at Claremont | 2024-11-02 | Y | 3 | 26.67 | 100% | 67% | 100% |
Data
| Purdue B | Purdue A | 10 | 10 | 0 | 20 |
| Chicago B | SIUE | 0 | 10 | 10 | 20 |
| Illinois Orange | Chicago A | 0 | 10 | 10 | 20 |
| Illinois Blue | Notre Dame | 0 | 10 | 10 | 20 |