8.Electromagnetic waves
medium

વિધુતચુંબકીય તરંગમાં વિધુતક્ષેત્ર અને ચુંબકીયક્ષેત્રની દિશા $\hat{ k }$ અને $2 \hat{ i }-2 \hat{ j },$ છે. તરંગની પ્રસરણ દિશા માનો એકમ સદિશ

A

$\frac{1}{\sqrt{2}}(\hat{ i }+\hat{j})$

B

$\frac{1}{\sqrt{5}}(\hat{ i }+2 \hat{ j })$

C

$\frac{1}{\sqrt{5}}(2 \hat{ i }+\hat{ j })$

D

$\frac{1}{\sqrt{2}}(\hat{j}+\hat{k})$

(JEE MAIN-2020)

Solution

$\hat{ E }=\hat{ k }$

$\overrightarrow{ B }=2 \hat{ i }-2 \hat{ j } \Rightarrow \hat{ B }=\frac{\overrightarrow{ B }}{| B |}=\frac{2 \hat{ i }-2 \hat{ j }}{2 \sqrt{2}}$

$\Rightarrow \hat{ B }=\frac{1}{\sqrt{2}}(\hat{ i }-\hat{j})$

Direction of wave propagation $=\hat{ C }=\hat{ E } \times \hat{ B }$

$\hat{ C }=\hat{ k } \times\left[\frac{1}{\sqrt{2}}(\hat{ i }-\hat{ j })\right]$

$\hat{ C }=\frac{1}{\sqrt{2}}(\hat{ k } \times \hat{ i }-\hat{ k } \times \hat{ j })$

$\hat{ C }=\frac{1}{\sqrt{2}}(\hat{ i }+\hat{ j })$

Standard 12
Physics

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