In the circuit shown, the current through the 4 Ω resistors is 1 amp when the points P and M are connected to a dc voltage source. The potential difference between the points M and N is.

• A: 1.5V
• B: 1.0V
• C: 0.5V
• D: 3.2V

To find the potential difference between points M and N in the given circuit, we need to analyze the current flowing through the resistors. Since the current through the 4 Ω resistors is 1 amp, we can use Ohm's Law, which states that Voltage (V) = Current (I) × Resistance (R).

Calculating Voltage Across Resistors

For each 4 Ω resistor, the voltage drop can be calculated as follows:

• Voltage (V) = Current (I) × Resistance (R)
• V = 1 A × 4 Ω = 4 V

Understanding the Circuit Configuration

If the resistors are in series, the total voltage drop across both resistors would be:

• Total Voltage Drop = 4 V + 4 V = 8 V

If they are in parallel, the voltage across each resistor remains the same, which is 4 V. However, since we are looking for the potential difference between points M and N, we need to consider how these points are connected in the circuit.

Finding the Potential Difference

Assuming points M and N are connected across one of the resistors, the potential difference would be equal to the voltage drop across that resistor. Since we have established that the voltage drop across one 4 Ω resistor with 1 A of current is 4 V, we need to determine how this relates to the options provided.

Evaluating the Options

Given the options:

• A: 1.5V
• B: 1.0V
• C: 0.5V
• D: 3.2V

Since the calculated voltage drop is 4 V, and none of the options match this directly, we need to consider the configuration of the circuit again. If the resistors are in a more complex arrangement, the effective voltage drop could be less than 4 V.

Upon reevaluation, if the potential difference between M and N is indeed less than the total voltage drop across the resistors, the correct answer would likely be the closest lower value. Therefore, the potential difference between points M and N is:

1.0V (Option B)