Answer:
√2 E
Explanation:
In an electromagnetic wave, the amplitude defines the energy a wave carries. That energy is carried along through fields which means larger the strength of the field, more work can it do on the charges in the field. This signifies that the wave carries more energy.
The wave energy is proportional to the square of its amplitude( [tex] E^2 [/tex] )
Given 18 ∝ [tex]E^{2}[/tex]
So, for 36, we multiply both sides with two
36 ∝ [tex]2E^2[/tex]
36W/m2 will have amplitude √2 E