Earth receives energy at the rate of `2.5"cal /cm"^2` min . Calculate the number of photons received on the Earth. Per `cm^2` per minute if the average wavelength of solar light is 500 nm. Take 1 calorie = 4.2 J

Explanation

To solve the problem of calculating the number of photons received on Earth per cm² per minute when the energy received is 2.5 cal/cm²/min and the average wavelength of solar light is 500 nm, we can follow these steps:

### Step 1: Convert Energy from Calories to Joules
We know that 1 calorie = 4.2 Joules. Therefore, we can convert the energy received in calories to joules.

\[ \text{Energy received} = 2.5 \, \text{cal/cm}^2/\text{min} \times 4.2 \, \text{J/cal} = 10.5 \, \text{J/cm}^2/\text{min} \]
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