Q=?Show transcribed image text
Q=?Show transcribed image text In many computer keyboards the switches under the keys consist of small parallel-plate capacitors (see figure). The key is attached to the upper plate, which is movable. When you push the key down, you push the upper plate toward the lower plate and you after the plate separation d and the capacitance. The capacitor is connected to an external circuit that maintains a constant potential difference Delta V across the plates. The change of capacitance therefore sends a pulse of charge from the capacitor into the computer circuit. Suppose that the initial plate separation is 4.00 times 10-3 m and the initial capacitance is 5.00 times10-15 F. The final plate separation (with the key fully depressed) is 1.00 times104m. The constant potential difference is 15.00 V. What is the change in capacitance when you depress the key? Capacitive keyboard switch.