Answered

What wavelength photon is required to excite a hydrogen from the n=1 state to the n=3 state? What is the lowest frequency photon that will be observed?

Answer :

Explanation:

It is given that,

Initial state of electron, [tex]n_i=1[/tex]

Final state of electron, [tex]n_f=3[/tex]

The wavelength of the excited electron is given by :

[tex]\dfrac{1}{\lambda}=R(\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2})[/tex]

Where

R is Rydberg's constant

[tex]\dfrac{1}{\lambda}=1.097\times 10^{7}\ J\times (\dfrac{1}{3^2}-\dfrac{1}{1^2})[/tex]

[tex]\lambda=-1.02\times 10^{-7}\ m[/tex]

or

[tex]\lambda=102\ nm[/tex]

Let f is the frequency of the observed photon. It is given by :

[tex]f=\dfrac{c}{\lambda}[/tex]

[tex]f=\dfrac{3\times 10^8\ m/s}{1.02\times 10^{-7}\ m}[/tex]

[tex]f=2.94\times 10^{15}\ Hz[/tex]

Hence, this is the required solution.

Answer:

1.032 x 10^-7 m, 2.9 x 10^15 Hz

Explanation:

n = 1 to n = 3

Rydberg's constant, R = 1.09 × 10^7 per metre

Use the formula for the wavelength

[tex]\frac{1}{\lambda }=R\left ( \frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}} \right )[/tex]

here, n1 = 1 and n2 = 3

[tex]\frac{1}{\lambda }=1.09\times 10^{7}\left ( \frac{1}{1^{2}}-\frac{1}{3^{2}} \right )[/tex]

[tex]\frac{1}{\lambda }=1.09\times 10^{7}\times \frac{8}{9}[/tex]

λ = 1.032 x 10^-7 m

Let the frequency is f.

Use the relation

v = f x λ

[tex]3 \times 10^8=f\times 1.032 \times 10^{-7}[/tex]

f = 2.9 x 10^15 Hz

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