Question

The intensity of a beam of monochromatic light ___________ with the increase in the concentration of the absorbing substance arithmetically.

(a) decrease exponentially

(b) increase exponentially

(c) decrease linearly

(d) increase linearly

I had been asked this question in my homework.

My query is from Laws of Photochemistry topic in section Photochemistry of Engineering Chemistry I

Answer 1

Correct choice is (a) decrease exponentially

The explanation is: As per Beer’s Law, the intensity of incident light decreases exponentially with the increase in concentration of the absorbing substance arithmetically. Mathematically, it is shown as follows: I = Io/e^kc.