# Lifetimes of the Molecules in the Excited States Are Often Measured by Using Pulsed Radiation Source of Duration Nearly in the Nano Second Range Calculate the Energy of the Source - Chemistry

Lifetimes of the molecules in the excited states are often measured by using pulsed radiation source of duration nearly in the nano second range. If the radiation source has the duration of 2 ns and the number of photons emitted during the pulse source is 2.5 × 1015, calculate the energy of the source.

#### Solution

v = 1/(2.0 xx 10^(9))

v = 5.0 xx 10^8 s^(-1)

Energy (E) of source = Nhν

Where,

N = number of photons emitted

h = Planck’s constant

Substituting the values in the given expression of (E):

E = (2.5 × 1015) (6.626 × 10–34 Js) (5.0 × 108 s–1)

E = 8.282 × 10–10 J

Hence, the energy of the source (E) is 8.282 × 10–10 J.

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#### APPEARS IN

NCERT Class 11 Chemistry Textbook
Chapter 2 Structure of Atom
Q 49 | Page 68