Verified Solution • 2025–26 Session moderate

QJEEM22Phaf1e: JEE Main 2022 Physics - Class 12 JEEM22Phaf1e Solution: If Electric field intensity of a uniform plane electromagnetic…

If Electric field intensity of a uniform plane electromagnetic wave is given as E=−301.6sin⁡(kz−ωt)a^x+452.4sin⁡(kz−ωt)a^yVmE = - 301.6\sin (kz - \omega t){\widehat a_x} + 452.4\sin (kz - \omega t){\widehat a_y}{V \over m} . Then magnetic intensity 'H' of this wave in Am −- 1 will be :

[Given : Speed of light in vacuum c=3×108c = 3 \times {10^8} ms −- 1, Permeability of vacuum μ0=4π×10−7{\mu _0} = 4\pi \times {10^{ - 7}} NA −- 2]

Multiple Choice Options

  • A +0.8sin⁡(kz−ωt)a^y+0.8sin⁡(kz−ωt)a^x+ 0.8\sin (kz - \omega t){\widehat a_y} + 0.8\sin (kz - \omega t){\widehat a_x}
  • B +1.0×10−6sin⁡(kz−ωt)a^y+1.5×10−6(kz−ωt)a^x+ 1.0 \times {10^{ - 6}}\sin (kz - \omega t){\widehat a_y} + 1.5 \times {10^{ - 6}}(kz - \omega t){\widehat a_x}
  • C −0.8sin⁡(kz−ωt)a^y−1.2sin⁡(kz−ωt)a^x- 0.8\sin (kz - \omega t){\widehat a_y} - 1.2\sin (kz - \omega t){\widehat a_x}
  • D −1.0×10−6sin⁡(kz−ωt)a^y−1.5×10−6sin⁡(kz−ωt)a^x- 1.0 \times {10^{ - 6}}\sin (kz - \omega t){\widehat a_y} - 1.5 \times {10^{ - 6}}\sin (kz - \omega t){\widehat a_x}

Step-by-Step Verified Solution

E→=−301.6sin⁡(kz−ωt)a^x+452.4sin⁡(kz−ωt)a^y\overrightarrow E = - 301.6\sin (kz - \omega t){\widehat a_x} + 452.4\sin (kz - \omega t){\widehat a_y}

E0x=301.6{E_{0x}} = 301.6

E0y=+452.4{E_{0y}} = + 452.4

E0=E0x2+E0y2{E_0} = \sqrt {E_{0x}^2 + E_{0y}^2}

Now, E0B0=C⇒B0=E0C=E0x2+E0y2C{{{E_0}} \over {{B_0}}} = C \Rightarrow {B_0} = {{{E_0}} \over C} = {{\sqrt {E_{0x}^2 + E_{0y}^2} } \over C}

Also, B^=C^×E^⇒k^×(E0xi^+E0yj^)E0x2+E0y2\widehat B = \widehat C \times \widehat E \Rightarrow \widehat k \times {{({E_{0x}}\widehat i + {E_{0y}}\widehat j)} \over {\sqrt {E_{0x}^2 + E_{0y}^2} }}

B^=−E0xj^−E0yi^E0x2+E0y2\widehat B = {{ - {E_{0x}}\widehat j - {E_{0y}}\widehat i} \over {\sqrt {E_{0x}^2 + E_{0y}^2} }}

B→=−E0xCsin⁡(kz−ωt)a^y−E0yCsin⁡(kz−ωt)a^x\overrightarrow B = - {{{E_{0x}}} \over C}\sin (kz - \omega t){\widehat a_y} - {{{E_{0y}}} \over C}\sin (kz - \omega t){\widehat a_x}

H→=B→μ0\overrightarrow H = {{\overrightarrow B } \over {{\mu _0}}}

H→=−E0xμ0Csin⁡(kz−ωt)a^y−E0yμ0Csin⁡(kz−ωt)a^x\overrightarrow H = - {{{E_{0x}}} \over {{\mu _0}C}}\sin (kz - \omega t){\widehat a_y} - {{{E_{0y}}} \over {{\mu _0}C}}\sin (kz - \omega t){\widehat a_x}

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