With respect to measuring the current in a circuit using the CRO, which of the following statements is/are correct?

I. A low-resistance standard resistor is connected in series with the circuit whose current is being measured.

II. The CRO is connected across the standard resistor to measure the voltage drop across it.

III. A high-resistance standard resistor is connected in parallel with the circuit where the current is being measured.

IV. The CRO is connected in series with the circuit whose current is being measured.

The correct answer is option 1.

Explanation

I. When measuring current using a CRO (Cathode Ray Oscilloscope), a low-resistance standard resistor is connected in series with the circuit to avoid significant voltage drops across the resistor. This helps in accurately measuring the current without affecting the circuit's behavior significantly.

II. The CRO is connected across the standard resistor because the voltage drop across the resistor is proportional to the current flowing through it. By measuring this voltage drop using the CRO, you can indirectly determine the current in the circuit.

III. This statement is incorrect. The standard resistor is connected in series, not parallel, to measure the current accurately.

This statement is incorrect. The CRO is not connected in series with the circuit being measured. It is connected across the standard resistor to measure the voltage drop across it, allowing for the calculation of current.