Answer to Question 1
The first operation in testing a capacitor is to discharge it. Do not discharge it by shorting out the terminals. This can damage the capacitor. To avoid electrical shock, the technician should never place fingers across the terminals before properly discharging the capacitor.
Answer to Question 2
Electronic devices may use the metal chassis where components are mounted as a common conductor. If you touch the metal chassis accidentally while there is power, you will receive a shock. Isolation transformers are used to break the circuit and protect the technician.
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Testing visual fields by confrontation
For the circuit in Figure 1, assume ideal diodes. The peak inverse voltage is approximately