A point source emitting uniformly in all directions is placed above a table top at a distance of 0.50 m from it. The luminous flux of the source is 1570 lumen. Find the illuminance at a small surface area of the table to a.directly below the source and b. at as distance of 0.80 m from the source.

Explanation

To solve the problem, we need to calculate the illuminance (E) at two different points on the table below a point light source. The illuminance is defined as the luminous flux (Φ) per unit area (A) and can be calculated using the formula:

\[ E = \frac{\Phi}{A} \]

Where:
- \( E \) is the illuminance in lux (lm/m²),
- \( \Phi \) is the luminous flux in lumens (lm),
- \( A \) is the area in square meters (m²).
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