A cell of e.m.f. 1.5 V, internal resistance 1 `Omega ` is connected to the resistors of 4 `Omega ` and `20 Omega ` in series. Draw a circuit diagram and calculate :
the voltage drop when the current is flowing.

Explanation

To solve the problem step by step, we will first draw the circuit diagram and then calculate the voltage drop when the current is flowing.

### Step 1: Draw the Circuit Diagram
We have a cell of EMF 1.5 V with an internal resistance of 1 Ω connected in series with two resistors: R1 = 4 Ω and R2 = 20 Ω.

**Circuit Diagram:**
```
+----[1Ω]----[4Ω]----[20Ω]-----
...