Two coherent light beams of intensity 2I and 18I are superposed with each other. The maximum and minimum possible intenstities in the resulting beam are
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 32I, 8I
$I_{max}∝|E_{max}|^2=(E_1+E_2)^2$
where,
$I_{max}$ = max. intensity
$I_{max}=(\sqrt{2I}+\sqrt{18I})^2$
$=I(\sqrt{2}+3\sqrt{2})^2=I(4\sqrt{2})^2$
$=32I$
$I_{min}∝|E_{min}|^2=(E_1-E_2)^2$
$=(\sqrt{2I}+\sqrt{18I})^2$
$=8I$