Incorrect statement: c) Difficult to tune

Explanation:

A Wien Bridge oscillator is a type of oscillator circuit that is widely used in audio frequency applications. It is known for its simplicity, low distortion, and good stability at the resonant frequency. However, it is not difficult to tune.

Key points:

1. Low distortion: The Wien Bridge oscillator is designed to produce a sinusoidal waveform with low distortion. This is achieved by using a feedback network that provides high gain at the resonant frequency and attenuates the harmonics.

2. Good stability at the resonant frequency: The Wien Bridge oscillator is inherently stable at the resonant frequency. It uses a frequency selective form of a Wheatstone bridge circuit, which provides a balanced condition at the resonance. This ensures that the oscillations are sustained without any significant frequency drift.

3. Easy tuning: Unlike some other oscillator circuits, the Wien Bridge oscillator is relatively easy to tune. The frequency of oscillation can be adjusted by changing the values of the resistors and capacitors in the circuit. By carefully selecting these components, the desired frequency can be obtained.

4. Frequency selective form of a Wheatstone bridge: The Wien Bridge oscillator is based on a frequency selective form of a Wheatstone bridge circuit. The bridge consists of two resistors and two capacitors arranged in a specific configuration. This configuration provides a feedback path that allows the circuit to oscillate at the resonant frequency determined by the values of the components.

Conclusion:

In summary, the incorrect statement for a Wien Bridge oscillator is that it is difficult to tune. On the contrary, it is relatively easy to tune by adjusting the values of the resistors and capacitors in the circuit. The oscillator is designed to provide low distortion and good stability at the resonant frequency, making it suitable for audio frequency applications.