An electric field in an e.m.wave is given by
`E=200 sin .(2pi)/lambda(ct-x)NC^-1`.
Find the energy contained in a cylinder of crossection `20 cm^2` and length 40 cm along the x-axis.

Explanation

To find the energy contained in a cylinder with a given electric field in an electromagnetic wave, we can follow these steps:

### Step 1: Identify the given parameters
The electric field is given by:
\[ E = 200 \sin\left(\frac{2\pi}{\lambda}(ct - x)\right) \, \text{N/C} \]
From this, we can identify:
- The amplitude of the electric field, \( E_0 = 200 \, \text{N/C} \).

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