A potentiometer wire of length 1.0 m has a resistance of `10 Omega`. It is connected to a 6 V battery in seried with a resistance of `5 Omega`. Determine the emf of the primary cell which gives a balance point at 40 cm.

Explanation

To solve the problem step by step, we will determine the EMF of the primary cell that gives a balance point at 40 cm on a potentiometer wire.

### Step 1: Understand the Circuit Setup
We have a potentiometer wire of length 1.0 m (100 cm) with a resistance of 10 Ω. It is connected to a 6 V battery in series with a resistance of 5 Ω.

### Step 2: Calculate Total Resistance
The total resistance in the circuit (R_total) is the sum of the resistance of the potentiometer wire (R_p) and the series resistance (R_s):
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