Circuit tester uses 

1. Open Circuit Identification: Circuit testers can determine if there is an open circuit, where the electrical current is interrupted or not flowing through the circuit as intended. This is useful for identifying breaks in wires or connections.
2. Short Circuit Detection: Short circuits occur when there is an unintended connection between different points in a circuit. Circuit testers can help locate and identify short circuits, which can be crucial for preventing electrical fires or damage to components.
3. Voltage Verification: Circuit testers can be used to verify the presence of voltage in a circuit. This is essential for ensuring that power is reaching the intended components or devices.
4. Continuity Testing: These testers are often used to check the continuity of a circuit, ensuring that there is a complete path for the electrical current. This is important for verifying the integrity of wires, switches, and other components.
5. Ground Fault Detection: Circuit testers can help identify ground faults, where the electrical current unintentionally flows to the ground. Ground faults can be hazardous, and a circuit tester can be used to locate and address these issues.
6. Outlet and Socket Testing: In residential and commercial settings, circuit testers are used to check the functionality of electrical outlets and sockets. This includes verifying proper wiring, grounding, and polarity.
7. Automotive Electrical Troubleshooting: Circuit testers are widely used in automotive diagnostics to identify and resolve electrical issues in vehicles. They can help pinpoint faults in wiring, fuses, and other components.
8. Appliance Repair: When appliances malfunction, circuit testers are employed to identify electrical problems within the appliances. This includes checking power cords, switches, and internal wiring.
9. Safety Checks: Circuit testers are essential for safety inspections, ensuring that electrical systems meet safety standards and regulations. They help identify potential hazards and prevent electrical accidents.
10. DIY Electrical Projects: Circuit testers are valuable tools for individuals undertaking do-it-yourself (DIY) electrical projects. They provide a means to verify the correctness and safety of electrical work.