Violet light `(lambda=4000A )`of intensity `4watt/m^(2)` falls normally on a surface of area `10cm xx 20cm`.Find (i) the energy received by the surface per second.(ii) the number of photons hitting the surface the surface per second,(iii) If surface is titled such that plane of the surface makes an angle `30^(@)`with light beam, find the number of photons hitting the surface per second.

Explanation

To solve the problem step by step, we will address each part of the question systematically.

### Given Data:
- Wavelength of violet light, \( \lambda = 4000 \, \text{Å} = 4000 \times 10^{-10} \, \text{m} \)
- Intensity of light, \( I = 4 \, \text{W/m}^2 \)
- Area of the surface, \( A = 10 \, \text{cm} \times 20 \, \text{cm} = 0.1 \, \text{m} \times 0.2 \, \text{m} = 0.02 \, \text{m}^2 \)

### (i) Energy received by the surface per second
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