# Beam remains Parallel!

Two converging lenses of same aperture size are placed with their principal axis coinciding. Their focal lengths are in the ratio $$K$$. When a light beam is incident parallel to their common principal axis, it is observed that final emergent beam is also parallel to their common principal axis. It is observed that when beam is incident from left intensity recorded on screen is $$I_1$$, but when positions of lenses are interchanged, the same point on screen records an intensity $$I_2$$. Then $$\large \frac{I_1}{I_2} = \frac{1}{K^x}$$ where $$x$$ can have 2 values. Find the sum of the two values of $$x$$.

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