Q15. A plane EM wave is propagating along $x$ direction. It has a wavelength of 4 mm . If electric field is in $y$ direction with the maximum magnitude of $60 \mathrm { Vm } ^ { - 1 }$, the equation for magnetic field is :\\
(1) $\mathrm { B } _ { z } = 2 \times 10 ^ { - 7 } \sin \left[ \frac { \pi } { 2 } \times 10 ^ { 3 } \left( x - 3 \times 10 ^ { 8 } \mathrm { t } \right) \right] \hat { \mathrm { k } } \mathrm { T }$\\
(2) $\mathrm { B } _ { z } = 60 \sin \left[ \frac { \pi } { 2 } \left( x - 3 \times 10 ^ { 8 } \mathrm { t } \right) \right] \hat { \mathrm { k } } \mathrm { T }$\\
(3) $\mathrm { B } _ { x } = 60 \sin \left[ \frac { \pi } { 2 } \left( x - 3 \times 10 ^ { 8 } \mathrm { t } \right) \right] \mathrm { i } \hat { T }$\\
(4) $\mathrm { B } _ { z } = 2 \times 10 ^ { - 7 } \sin \left[ \frac { \pi } { 2 } \left( x - 3 \times 10 ^ { 8 } \mathrm { t } \right) \right] \hat { \mathrm { k } } \mathrm { T }$