A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetising current of 1.2 A?

Explanation

To solve the problem, we need to find the magnetic field \( B \) in the core of a Rowland ring given the mean radius, number of turns, relative permeability, and magnetizing current. We will follow these steps:

### Step 1: Convert the Mean Radius to Meters
The mean radius \( R \) is given as 15 cm. To convert this to meters:
\[ R = 15 \text{ cm} = 15 \times 10^{-2} \text{ m} = 0.15 \text{ m} \]

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