JEE Main 20202 SeptemberEvening Shift
- Exam
- JEE Main
- Year
- 2020
- Date
- 2 September
- Shift
- Evening Shift
- Subject
- Physics
- Chapter
- Electromagnetic Waves
JEE Main 2020 · 2 September · Evening Shift · Physics · Electromagnetic Waves
In a plane electromagnetic wave, the directions of electric field...
In a plane electromagnetic wave, the directions of electric field and magnetic field are represented by\overset{^}{k} and 2\overset{^}{i} - 2\overset{^}{j}, respectively. What is the unit vector along direction of propagation of the wave.
Options
- A\dfrac{1}{\sqrt{2}} ( \overset{^}{i} + \overset{^}{j} )
- B\dfrac{1}{\sqrt{2}} ( \overset{^}{j} + k )
- C\dfrac{1}{\sqrt{5}} ( \overset{^}{i} + 2\overset{^}{j} )
- D\dfrac{1}{\sqrt{5}} ( 2\overset{^}{i} + \overset{^}{j} )
Correct answer
A. \dfrac{1}{\sqrt{2}} ( \overset{^}{i} + \overset{^}{j} )
Step-by-step solution
\overset{^}{E} \times \overset{^}{B} = \dfrac{1}{\sqrt{2}}\left|\begin{cases}\overset{^}{i} & \overset{^}{j} & \overset{^}{k} \\ 0 & 0 & 1 \\ 1 & - 1 & 0\end{cases}\right| = \dfrac{\overset{^}{i} + \overset{^}{j}}{\sqrt{2}} ⇒ \overset{^}{c} = \dfrac{\overset{^}{i} + \overset{^}{j}}{\sqrt{2}}