Before closing the circuit switch, which check should be performed?

• A. Always check polarities before closing the switch
• B. Tap the meter to avoid sticking
• C. Switch off the current when not measuring
• D. Check that connections are clean

Answer: (A)

Before turning the circuit on, make sure the connections have the correct polarity. This matters because many components are directional and only operate correctly when the positive and negative terminals are connected as intended. If polarity is reversed, a diode, LED, or electrolytic capacitor can be damaged, the circuit may not function, and readings from instruments can be wrong. Checking polarity helps protect components and ensures you get an accurate measurement when you switch the circuit on. While keeping connections clean and turning off power when not measuring are good safety habits, they don’t prevent damage from incorrect polarity—the main safeguard is getting the polarity right first.