Question 133: EM waves

Question

The magnetic field of a plane electromagnetic
wave is given by :
$$$\overline B  = {B_0}\widehat i\left[ {\cos (kz - \omega t)} \right] + {B_i}\widehat j\cos (kz + \omega t)$$$
B0 = 3 × 10–5 T and B1 = 2 × 10–6 T.
The rms
value of the force experienced by a stationary
charge Q = 10–4 C at z = 0 is closest to :

Accepted Answer

Maximum electric field E = (B) (C)
$$\overrightarrow {{E_0}}  = \left( {3 	imes {{10}^{   - 5}}} ight)c\left( { - \widehat j} ight)$$
$$\overrightarrow {{E_1}}  = \left( {2 	imes {{10}^{   - 6}}} ight)c\left( { - \widehat i} ight)$$
Maximum force
$${\overrightarrow F _{net}} = {10^{ - 4}} 	imes 3 	imes {10^8}\sqrt {{{\left( {3 	imes {{10}^{ - 5}}} ight)}^2} + {{\left( {2 	imes {{10}^{ - 6}}} ight)}^2}}  = 0.9N$$
$${F_{rms}} = {{{F_0}} \over {\sqrt 2 }} = 0.6\,N$$ (approx)

Answer

0.6 N

Answer

0.9 N

Answer

3 × 10–2 N

Answer

0.1 N

EM waves

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