The Assumed Voltage formula is used when the source or branch voltage is not known and can be used to solve for the actual resistance total of the circuit.

The Assumed Voltage formula is used when the source or branch voltage is not known and can be used to solve for the actual resistance total of the circuit.

• A. Source or branch current
• B. Source or branch voltage
• C. Source or branch resistance
• D. Source or branch power

Answer: (B)

When the supply voltage isn’t known, using the Assumed Voltage method starts with picking a convenient voltage to apply across the circuit and then using the known current to find the total resistance. This is just Ohm’s law in reverse: R_total = V_assumed / I. By dividing the assumed voltage by the measured current, you determine the total resistance the circuit presents. Once you have R_total, you can recover the actual voltage the source would produce with V_actual = I × R_total. So the quantity you’re setting as the assumption is the source or branch voltage, which is why this approach uses voltage as the starting point. If the actual voltage were known, you’d simply use V = I × R to find the resistance directly.

When the supply voltage isn’t known, using the Assumed Voltage method starts with picking a convenient voltage to apply across the circuit and then using the known current to find the total resistance. This is just Ohm’s law in reverse: R_total = V_assumed / I. By dividing the assumed voltage by the measured current, you determine the total resistance the circuit presents. Once you have R_total, you can recover the actual voltage the source would produce with V_actual = I × R_total. So the quantity you’re setting as the assumption is the source or branch voltage, which is why this approach uses voltage as the starting point. If the actual voltage were known, you’d simply use V = I × R to find the resistance directly.