JEE Main 2015 · 11 Apr · Shift 1 · Physics Q23

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PhysicsSingle correct+4 / -1Question 23 of 90

For plane electromagnetic waves propagating in the $z$ direction, which one of the following combination gives the correct possible direction for $\vec E$ and $\vec B$ field respectively ?

\left(\hat i+2\hat j\right)

and

\left(2\hat i-\hat j\right)

\left(-2\hat i-3\hat j\right)

and

\left(3\hat i-2\hat j\right)

\left(2\hat i+3\hat j\right)

and

\left(\hat i+2\hat j\right)

\left(3\hat i+4\hat j\right)

and

\left(4\hat i-3\hat j\right)

Answer and worked solution

Official answer: B

Need $\vec E\perp\vec B$ with $\vec E\times\vec B$ along $+\hat z$ . For (2): $(-2,-3)\cdot(3,-2)=-6+6=0$ ✓. The z-component of $\vec E\times\vec B$ is $(-2)(-2)-(-3)(3)=13>0$ ✓.

Topics:Properties of EM waves

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JEE Main 2015 · 11 Apr · Shift 1, Physics question 23