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Home » Suppose that the electric field part of an electromagnetic wave in vacuum is (a) What is the direction of propagation?(b) What is the wavelength ?
Suppose that the electric field part of an electromagnetic wave in vacuum is E=\{(3.1 \left.\mathrm{N} / \mathrm{C}) \cos \left[(1.8 \mathrm{rad} / \mathrm{m}) \mathrm{y}+\left(5.4 \times 10^{6} \mathrm{rad} / \mathrm{s}\right) \mathrm{t}\right]\right\}^{\wedge} \mathrm{i}
(a) What is the direction of propagation?
(b) What is the wavelength \lambda ?
CBSE | Class 12 | Electromagnetic Waves | NCERT | Physics
Suppose that the electric field part of an electromagnetic wave in vacuum is E=\{(3.1 \left.\mathrm{N} / \mathrm{C}) \cos \left[(1.8 \mathrm{rad} / \mathrm{m}) \mathrm{y}+\left(5.4 \times 10^{6} \mathrm{rad} / \mathrm{s}\right) \mathrm{t}\right]\right\}^{\wedge} \mathrm{i}
(a) What is the direction of propagation?
(b) What is the wavelength \lambda ?

(a) The motion is going in the opposite direction of the y-axis. To put it another way, along -j.

(b) The given equation is compared with the equation and we get,

E=E_{0} \cos (k y+\omega t)

\Rightarrow \mathrm{k}=1.8 \mathrm{rad} / \mathrm{s}

\omega=5.4 \times 10^{6} \mathrm{rad} / \mathrm{s}

\lambda=2 \pi / \mathrm{k}=(2 \times 3.14) / 1.8=3.492 \mathrm{~m}

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