Calculate the number of photons emitted per second by a 10 W sodium vapour lamp. Assume that 60% of the consumed energy is converted into light. Wavelengths of sodium light =590nm.

Explanation

To calculate the number of photons emitted per second by a 10 W sodium vapor lamp, we will follow these steps:

### Step 1: Calculate the useful energy converted into light
The lamp consumes 10 W of power, but only 60% of this energy is converted into light.

\[ \text{Useful Energy} = \text{Total Power} \times \text{Efficiency} \]
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