Diagram 1: EMF, Internal Resistance, and Terminal Voltage
ε r (internal) R (external) → I A B V_AB = ε − Ir (terminal voltage)| Label | Meaning |
|---|---|
| ε | EMF of cell (V) |
| r | Internal resistance () |
| R | External load resistance () |
| I | Current = ε/(R+r) |
| V_AB | Terminal voltage = ε − Ir |
| A, B | Terminals of the cell |
Diagram 2: Wheatstone Bridge
G P Q R S Balance: P/Q = R/S → I_G = 0| Node | Description |
|---|---|
| A (top) | Positive terminal of battery |
| C (bottom) | Negative terminal of battery |
| B (left) | Junction between P and R |
| D (right) | Junction between Q and S |
| G | Galvanometer (B to D) |
| Balance | V_B = V_D when P/Q = R/S |