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Classically, it was expected that an orbiting electron would emit radiation of the same frequency as its orbit frequency. We have often noted that classical behaviour is observed in the limit of large quantum numbers. Does it work in this case? (a) Show that the photon energy for the smallest possible energy jump at the 鈥渓ow-n-end鈥 of the hydrogen energies is 3|E0|/n3, while that for the smallest jump at the 鈥渉igh-n-end鈥 is 2|E0|/n3, where E0is hydrogen鈥檚 ground-state energy. (b) Use F=ma to show that the angular velocity of a classical point charge held in orbit about a fixed-point charge by the coulomb force is given by =e2/4蟺蔚0mr3. (c) Given that r=n2a0, is this angular frequency equal to the minimum jump photon frequency at either end of hydrogen鈥檚 allowed energies?

Short Answer

Expert verified

(a) The photon energy released in the smallest possible jumps on low and high- sides are 3|E0|/4and 2|E0|/n3respectively, where E0is hydrogen鈥檚 ground-state energy.

(b) Angular velocity of the point charge e2/4蟺蔚0mr3.

(c) Angular frequency of the photon is 2E0/hn3(matching the high- end).

Step by step solution

01

(a) Energy of smallest possible jump at low and high-  end:

The energy of an orbit can be defined as the required energy to make the electron jump to infinity or the energy released when an electron from infinity is brought to that orbit.

As you know that energy of an orbit 鈥榥鈥 can be given by:

En=-|E0|n2

Where, |E0|is the Energy of hydrogen鈥檚 ground state.

If the smallest possible jump at low-n end is 12, Its energy can be calculated as

E12=E2-E1=E022+E012=3E04

Now, let n and n-1 are the orbits for jump in the high-n end, then their energy difference can be calculated as

En-1n=En-En-1=-E0n2+E0n-12=E02n-1n2n-12

If n is high, you can write the above expression as E0n3.

Hence, the photon energy released in the smallest possible jumps on low and high-n sides are 3E0/4and 2E0/n3respectively, where E0is hydrogen鈥檚 ground-state energy.

02

(b) Angular velocity of the classical point charge:

Given,

F=ma 鈥.. (1)

As you know that Coulomb force between two charges separated by a distance r is given as,

F=e24蟿蟿蔚0r2 鈥.. (2)

You also know that acceleration of the charge can be written as

a=2r 鈥.. (3)

Now, by using equations (2) and (3) in equation (1) you get,

e24蟿蟿蔚0r2=m蝇2r

=e24蟿蟿蔚0mr3 鈥.. (4)

Hence, the angular velocity of point charge is =e24蟿蟿蔚0mr3.

03

Angular frequency of the photon:

Consider the given equation for angular frequency as below.

r=a0n2 鈥.. (5)

Now, by using eq. (5) in eq. (4), you get,

=e24蟿蟿蔚0ma0n63

If,a0=4蟿蟿蔚0h2/me2

=e24蟿蟿蔚04蟿蟿蔚0h2/me23n6=me424蟿蟿蔚02h22h1n=2E0h1n3

Hence, the angular frequency of photon 2E0h1n3which matches with the high-n end side.

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