The 20 candela bulb was replaced with a 50 candela bulb. How many times does the illumination of the table

The 20 candela bulb was replaced with a 50 candela bulb. How many times does the illumination of the table above the lamp change?

In both cases, only the light intensity of the bulb changed. Neither the table area nor the solid angle has changed, so these values can be reduced.

Let us find the change in illumination ΔЕ = Е2 / Е1.

E = F (luminous flux, lumen) / S (surface area, m2);

Ф = I (luminous intensity, candela) * w (solid angle, steradian).

We get a direct relationship:

ΔЕ = Е2 / Е1 = (I2 * w / S) / (I1 * w / S) = I2 / I1 = 50/20 = 2.5.

Answer: the illumination of the table will increase 2.5 times.