Introduction:
A Cathode Ray Oscilloscope (CRO) is a commonly used electronic device that is used to measure and display electrical signals. It is a versatile instrument that can be used for various measurements, including voltage, current, frequency, and power. However, there is one limitation in using a CRO for direct measurement of power.

Explanation:
Voltage Measurement:
A CRO can be used to directly measure voltage by connecting the probe to the circuit or component under test. The vertical deflection of the electron beam on the screen of the CRO is proportional to the input voltage. By calibrating the CRO, the voltage can be accurately measured.

Current Measurement:
To measure current using a CRO, an external shunt resistor or a current probe is required. The current flowing through the shunt resistor or the current probe generates a voltage that can be measured using the CRO. By knowing the resistance or sensitivity of the shunt resistor or current probe, the current can be calculated.

Frequency Measurement:
A CRO can also be used to measure the frequency of an input signal. By adjusting the timebase of the CRO, the number of cycles of the input waveform displayed on the screen can be counted. By knowing the time period of one cycle, the frequency can be calculated.

Power Measurement:
Unlike voltage, current, and frequency, a CRO cannot directly measure power. Power is the product of voltage and current, and a CRO measures these quantities separately. To measure power, a CRO would need to have built-in circuitry or additional components to perform the multiplication of voltage and current.

Conclusion:
In conclusion, a CRO is a versatile instrument that can be used for various measurements, including voltage, current, and frequency. However, it cannot be used for direct measurement of power. To measure power, additional circuitry or components are required.

Voltage