A potentiometer wire of length 10 m and resistance `20 Omega` is connected in series with a 25 V battery and an external resistance `30 Omega`. A cell of emf E in secondary circuit is balanced by 250 cm long potentiometer wire. The value of E in volt) is `X/10`. The value of x is______

Explanation

To solve the problem, we will follow these steps:

### Step 1: Calculate the total resistance in the circuit
The total resistance \( R_t \) in the circuit is the sum of the resistance of the potentiometer wire and the external resistance:
\[ R_t = R_{\text{pot}} + R_{\text{ext}} = 20 \, \Omega + 30 \, \Omega = 50 \, \Omega \]

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