Question

Let $n_r$ and $n_b$ be respectively the number of photons emitted by a red bulb and a blue bulb of equal power in a given time

• A. $n_r=n_b$
• B. $n_r<n_b$
• C. $n_r>n_b$
• D. the information is insufficient to get a relation between $n_r$ and $n_b$

Answer 1

Answer: (C)

$P_{Red}=P_{Blue}$
$n_r\frac{hc}{{\lambda }_r}=n_b\frac{hc}{{\lambda }_b}$
$\frac{n_r}{n_b}=\frac{{\lambda }_r}{{\lambda }_b}$
As ${\lambda }_r>{\lambda }_b$
$\therefore$ $n_r>n_b$