A copper wire having resistance 0.01 ohm in each metre is used to wind a 400 turn solenoid of radius 1.0 cm and length 20 cm. Find the emf of a battery which when connected across the solenoid will cause a magnetic field of `(1.0 xx 10^-2)` T near the centre of the solenoid.

Explanation

To solve the problem step by step, let's break it down as follows:

### Step 1: Identify Given Data
- Resistance per meter of the copper wire, \( R' = 0.01 \, \Omega/m \)
- Number of turns in the solenoid, \( N = 400 \)
- Length of the solenoid, \( L = 20 \, cm = 0.2 \, m \)
- Radius of the solenoid, \( r = 1 \, cm = 0.01 \, m \)
- Desired magnetic field at the center of the solenoid, \( B = 1.0 \times 10^{-2} \, T \)
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