Question

Check the continuity of the given circuit by using multimeter.

Hint:

Never perform a continuity test on a live circuit. Always disconnect the power source first. If testing a component that is part of a larger circuit board, you may need to isolate it by desoldering one end to get an accurate reading, as other components in parallel can give a false continuity reading.

Answer 1

Step 1: Understanding the Concept:
Continuity means there is a complete, unbroken path for current to flow. A continuity test is used to check for breaks in wires, fuses, or connections in a circuit. A multimeter in continuity mode sends a small current through the circuit and detects if it flows from one probe to the other. If the path is complete, the multimeter typically emits an audible beep and displays a low resistance value (close to 0 \(\Omega\)).
Step 2: Apparatus Required:
- A digital multimeter with a continuity function. - The circuit to be tested.
Step 3: Detailed Procedure:
1. Safety First: Ensure that the circuit to be tested is de-energized. There should be no power source connected to it. Testing a live circuit for continuity can damage the multimeter and be dangerous.
2. Set the Multimeter: Turn the dial of the multimeter to the continuity setting. This is often indicated by a symbol that looks like a sound wave or a diode symbol.
3. Test the Multimeter: Before testing the circuit, touch the two probes of the multimeter together. It should beep, confirming that the multimeter itself is working correctly. The display should show a value very close to zero.
4. Test the Circuit: Place the two probes at the two points between which you want to check for continuity. For example, to check a single wire, place one probe at each end. To check a switch, place one probe on each terminal and operate the switch.
5. Interpret the Results: - Beep and Low Reading (\(\sim 0 \, \Omega\)): This indicates good continuity. There is a complete path between the two points. - No Beep and 'OL' (Overload/Open Loop): This indicates no continuity. There is a break in the circuit between the two points. - No Beep and High Resistance Reading: This may indicate a poor connection or a component with high resistance in the path.
Step 4: Application:
This test can be used to check: - If a wire is broken internally. - If a fuse has blown. - If a switch is working correctly (shows continuity when closed, and open circuit when open). - If a solder joint is making a good connection.