Question

Number of photons emitted by a 50 W lamp in 5 hour ${\lambda }_{photon}=589A^0$_____________.

• A. $2.7\times {10}^{24}$
• B. $2.7\times {10}^{25}$
• C. $2.7\times {10}^{26}$
• D. $2.7\times {10}^{27}$

Answer 1

The correct option is A $2.7\times {10}^{24}$

Since, $1W=1J/s$

Therefor, $50W=50J/s$

We know that, Energy $=\frac{h_c}{\lambda }=\frac{1242}{5893}$ $\times 1.6\times {10}^{-19}\times 10$

$\therefore$ $E=3.372\times {10}^{-19}J$

$\because$ Power $=\frac{E}{t.50}=\left(\frac{3.372}{5\times 3600}\right)m=2.66\times {10}^{24}$