Question 90: EM waves

Question

An EM wave propagating in x-direction has a wavelength of 8 mm. The electric field vibrating y-direction has maximum magnitude of 60 Vm$$-$$1. Choose the correct equations for electric and magnetic fields if the EM wave is propagating in vacuum :

Accepted Answer

In first 3 options speed of light is 3 $$	imes$$ 10
8
m/sec and in the fourth option it is 4 $$	imes$$ 10
8
m/sec.
Using
E = CB
We can check the option is B.

Answer

$${E_y} = 60\sin \left[ {{\pi  \over 4} 	imes {{10}^3}(x - 3 	imes {{10}^8}t)} ight]\widehat j\,\,V{m^{ - 1}}$$
$${B_z} = 2\sin \left[ {{\pi  \over 4} 	imes {{10}^3}(x - 3 	imes {{10}^8}t)} ight]\widehat k\,\,T$$

Answer

$${E_y} = 60\sin \left[ {{\pi  \over 4} 	imes {{10}^3}(x - 3 	imes {{10}^8}t)} ight]\widehat j\,\,V{m^{ - 1}}$$
$${B_z} = 2 	imes {10^{ - 7}}\sin \left[ {{\pi  \over 4} 	imes {{10}^3}(x - 3 	imes {{10}^8}t)} ight]\widehat k\,\,T$$

Answer

$${E_y} = 2 	imes {10^{ - 7}}\sin \left[ {{\pi  \over 4} 	imes {{10}^3}(x - 3 	imes {{10}^8}t)} ight]\widehat j\,\,V{m^{ - 1}}$$
$${B_z} = 60\sin \left[ {{\pi  \over 4} 	imes {{10}^3}(x - 3 	imes {{10}^8}t)} ight]\widehat k\,\,T$$

Answer

$${E_y} = 2 	imes {10^{ - 7}}\sin \left[ {{\pi  \over 4} 	imes {{10}^4}(x - 4 	imes {{10}^8}t)} ight]\widehat j\,\,V{m^{ - 1}}$$
$${B_z} = 60\sin \left[ {{\pi  \over 4} 	imes {{10}^4}(x - 4 	imes {{10}^8}t)} ight]\widehat k\,\,T$$

EM waves

An EM wave propagating in x-direction has a wavelength of 8 mm. The electric field vibrating y-direction has maximum magnitude of 60 Vm$-$1. Choose the correct equations for electric and magnetic fields if the EM wave is propagating in vacuum :

Choose the correct answer: