حساب القوة الدافعة الكهربائية $V_B$

Hi fares, let's solve this physics problem together. We need to find the value of the electromotive force V B for this part of an electric circuit.

First, let's look at the junction at the top right. We have two amperes entering from the right and one ampere leaving to the left through the upper branch.

By applying Kirchhoff's Current Law at this junction, the current entering must equal the current leaving. Since two amperes enter and one ampere leaves to the left, the remaining one ampere must flow downwards through the twenty ohm resistor.

Now, let's focus on the closed loop on the left side of the circuit. We will apply Kirchhoff's Voltage Law around this loop, moving clockwise.

Starting from the battery, we have positive V B. Then we subtract the voltage drops across each resistor: one ampere times two ohms, one ampere times twenty ohms, and one ampere times three ohms.