Direct Deflection Method and its principle

The direct deflection method is used for measuring the resistance of a coil or a conductor. It is based on the principle of the Ammeter-Voltmeter method.

Ammeter-Voltmeter Method

The Ammeter-Voltmeter method is a technique used to measure the resistance of a coil or a conductor by using an ammeter and a voltmeter. In this method, a known current is passed through the coil or conductor, and the corresponding voltage drop is measured using the voltmeter. By applying Ohm's law, the resistance can be calculated as the ratio of voltage to current.

Principle of the Direct Deflection Method

The direct deflection method is a modification of the Ammeter-Voltmeter method. In this method, the unknown resistance is connected in parallel with a known resistance, and a constant current is passed through them. The current is divided between the two resistances according to their respective values. A voltmeter is connected across the known resistance, and its reading is noted.

The principle behind the direct deflection method is that when a current is passed through a resistance, a voltage drop is produced across it. This voltage drop is directly proportional to the resistance value. By measuring the voltage drop across the known resistance using the voltmeter, the resistance of the unknown resistance can be determined.

Advantages of the Direct Deflection Method

1. Simple setup: The direct deflection method requires only a known resistance, a voltmeter, and a constant current source. The setup is relatively simple and easy to implement.

2. Accurate measurements: By using a voltmeter to directly measure the voltage drop across the known resistance, accurate measurements of resistance can be obtained.

3. Wide range of resistance measurement: The direct deflection method can be used to measure a wide range of resistance values, from low to high.

4. Non-destructive testing: The direct deflection method does not damage or alter the resistance being measured, making it suitable for non-destructive testing.

Conclusion

The direct deflection method is based on the principle of the Ammeter-Voltmeter method. It is a simple and accurate technique for measuring resistance. By connecting the unknown resistance in parallel with a known resistance and measuring the voltage drop across the known resistance, the resistance of the unknown can be determined. This method is widely used in electrical engineering for various applications.