Advertisements
Advertisements
प्रश्न
A filter transmits only the radiation of wavelength greater than 440 nm. Radiation from a hydrogen-discharge tube goes through such a filter and is incident on a metal of work function 2.0 eV. Find the stopping potential which can stop the photoelectrons.
Advertisements
उत्तर
Wavelength of radiation coming from filter, λ = 440 nm
Work function of metal, ϕ = 2 eV
Charge of the electron, e = 1.6 × 10-9 C
Let V0 be the stopping potential.
From Einstein's photoelectric equation,
`(hc)/lamda - ø=eV_0`
Here,
h =Planck constant
c = Speed of light
λ = Wavelength of radiation
`(4.14 xx 10^-15xx3xx10^8)/(440xx10^-9)- 2eV = eV_0`
⇒ `eV_0 = ((1242)/440 - 2)eV = 0.823`
⇒ `V_0 = 0.823` Volts
APPEARS IN
संबंधित प्रश्न
The longest wavelength doublet absorption transition is observed at 589 and 589.6 nm. Calculate the frequency of each transition and energy difference between two excited states.
If the velocity of the electron in Bohr’s first orbit is 2.19 × 106 ms-1, calculate the de Broglie wavelength associated with it.
State Bohr postulate of hydrogen atom that gives the relationship for the frequency of emitted photon in a transition.
Evaluate Rydberg constant by putting the values of the fundamental constants in its expression.
Consider a neutron and an electron bound to each other due to gravitational force. Assuming Bohr's quantization rule for angular momentum to be valid in this case, derive an expression for the energy of the neutron-electron system.
How are various lines of Lyman series formed? Explain on the basis of Bohr’s theory.
The radius of the third Bohr orbit for hydrogen atom is ____________.
For an electron in the second orbit of hydrogen, what is the moment of momentum as per the Bohr's model?
According to Bohr's model of hydrogen atom, an electron can revolve round a proton indefinitely, if its path is ______.
Ratio of longest to shortest wavelength in Balmer series is ______.
In form of Rydberg's constant R, the wave no of this first Ballmer line is
The Bohr model for the spectra of a H-atom ______.
- will not be applicable to hydrogen in the molecular from.
- will not be applicable as it is for a He-atom.
- is valid only at room temperature.
- predicts continuous as well as discrete spectral lines.
The inverse square law in electrostatics is |F| = `e^2/((4πε_0).r^2)` for the force between an electron and a proton. The `(1/r)` dependence of |F| can be understood in quantum theory as being due to the fact that the ‘particle’ of light (photon) is massless. If photons had a mass mp, force would be modified to |F| = `e^2/((4πε_0)r^2) [1/r^2 + λ/r]`, exp (– λr) where λ = mpc/h and h = `h/(2π)`. Estimate the change in the ground state energy of a H-atom if mp were 10-6 times the mass of an electron.
State Bohr's postulate to explain stable orbits in a hydrogen atom. Prove that the speed with which the electron revolves in nth orbit is proportional to `(1/"n")`.
Given below are two statements:
Statements I: According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in positive charges on the nucleus as there is no strong hold on the electron by the nucleus.
Statement II: According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increase with a decrease in principal quantum number.
In light of the above statements, choose the most appropriate answer from the options given below:
A hydrogen atom in is ground state absorbs 10.2 eV of energy. The angular momentum of electron of the hydrogen atom will increase by the value of ______.
(Given, Planck's constant = 6.6 × 10-34 Js)
The energy of an electron in the nth orbit of the hydrogen atom is En = -13.6/n2eV. The negative sign of energy indicates that ______.
Calculate the shortest wavenumber in hydrogen spectrum of Lyman series. (RH = 109677 cm−1)
