Final answer:
To find the voltage V0 and current I, one must apply Ohm's law to the resistors in the circuit, calculating the voltage drop across each resistor by multiplying the current by the resistor's value.
Step-by-step explanation:
To calculate the voltage V0 and current I in a circuit using the constant voltage drop model, we use Ohm's law, which states that the voltage drop V across a resistor when a current I flows through it is V = IR, where I is the current in amperes (A) and R is the resistance in ohms (Ω). Applying this to a resistor R1, the voltage drop V1 would be V1 = IR1. The total current I can be found by dividing the total voltage V by the total resistance Rtot. As given in the example, with VR being 12.0 V and Rtot being 5.11 Ω, the total current I is 2.35 A.
In cases where there are multiple resistors in series, such as R1, R2, and R3, the voltage drop across each resistor can be calculated individually using the formula V = IR for each resistor.