To determine the frequency of the radiation emitted when the electron transitions from \( n=2 \) to \( n=1 \) for a hydrogen-like ion, we can use the Rydberg formula for the frequency of emitted radiation:
v = RZ^2\left(\frac{1}{n_1^2} - \frac{1}{n_2^2}\right)where:
Given that the transition from \( n=3 \) to \( n=1 \) has a frequency of \( 2.92 \times 10^{15} \) Hz, we can write this equation as:
2.92 \times 10^{15} = RZ^2\left(\frac{1}{1^2} - \frac{1}{3^2}\right)Simplifying:
2.92 \times 10^{15} = RZ^2\left(1 - \frac{1}{9}\right) = RZ^2\left(\frac{8}{9}\right)We need to find the frequency for the transition from \( n=2 \) to \( n=1 \):
v = RZ^2\left(\frac{1}{1^2} - \frac{1}{2^2}\right) = RZ^2\left(1 - \frac{1}{4}\right) = RZ^2\left(\frac{3}{4}\right)Dividing the two expressions:
\frac{v}{2.92 \times 10^{15}} = \frac{\left(\frac{3}{4}\right)}{\left(\frac{8}{9}\right)}This simplifies to:
v = 2.92 \times 10^{15} \times \frac{3}{4} \times \frac{9}{8}Simplifying the calculation:
v = 2.92 \times 10^{15} \times \frac{27}{32}Calculating the value:
v = \frac{78.84}{32} \times 10^{15} = 2.46 \times 10^{15} \text{ Hz}Therefore, the frequency of the radiation emitted when transitioning from \( n=2 \) to \( n=1 \) is \( 2.46 \times 10^{15} \) Hz. The correct answer is $2.46 \times 10^{15}$.