Why is ac and dc coupling switch given in a CRO?

AC and DC coupling switches in a Cathode Ray Oscilloscope (CRO) allow users to select how the input signal is processed. AC coupling blocks any DC component of the signal, allowing for the observation of small AC variations superimposed on a larger DC level, which is helpful in analyzing fluctuating signals. In contrast, DC coupling allows both AC and DC components to be measured, providing a complete view of the signal’s behavior. This versatility is essential for different types of signal analysis in electronic testing.