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 energy associated with the first orbit in the hydrogen atom is - 2.18 × 10-18 J atom-1. What is the energy associated with the fifth orbit?
Draw a neat, labelled energy level diagram for H atom showing the transitions. Explain the series of spectral lines for H atom, whose fixed inner orbit numbers are 3 and 4 respectively.
Lifetimes of the molecules in the excited states are often measured by using pulsed radiation source of duration nearly in the nanosecond range. If the radiation source has a duration of 2 ns and the number of photons emitted during the pulse source is 2.5 × 1015, calculate the energy of the source.
In accordance with the Bohr’s model, find the quantum number that characterises the earth’s revolution around the sun in an orbit of radius 1.5 × 1011 m with orbital speed 3 × 104 m/s. (Mass of earth = 6.0 × 1024 kg)
In Bohr’s model of the hydrogen atom, the radius of the first orbit of an electron is r0 . Then, the radius of the third orbit is:
a) `r_0/9`
b) `r_0`
c) `3r_0`
d) `9r_0`
State Bohr postulate of hydrogen atom that gives the relationship for the frequency of emitted photon in a transition.
Find the wavelength of the radiation emitted by hydrogen in the transitions (a) n = 3 to n= 2, (b) n = 5 to n = 4 and (c) n = 10 to n = 9.
A neutron having kinetic energy 12.5 eV collides with a hydrogen atom at rest. Nelgect the difference in mass between the neutron and the hydrogen atom and assume that the neutron does not leave its line of motion. Find the possible kinetic energies of the neutron after the event.
State any two Bohr’s postulates and write the energy value of the ground state of the hydrogen atom.
Using Bohr's postulates derive the expression for the radius of nth orbit of the electron.
Hydrogen atom has only one electron, so mutual repulsion between electrons is absent. However, in multielectron atoms mutual repulsion between the electrons is significant. How does this affect the energy of an electron in the orbitals of the same principal quantum number in multielectron atoms?
Consider two different hydrogen atoms. The electron in each atom is in an excited state. Is it possible for the electrons to have different energies but same orbital angular momentum according to the Bohr model? Justify your answer.
On the basis of Bohr's model, the approximate radius of Li++ ion in its ground state ifthe Bohr radius is a0 = 53 pm :
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.
If a proton had a radius R and the charge was uniformly distributed, calculate using Bohr theory, the ground state energy of a H-atom when (i) R = 0.1 Å, and (ii) R = 10 Å.
The electron in a hydrogen atom first jumps from the third excited state to the second excited state and subsequently to the first excited state. The ratio of the respective wavelengths, λ1/λ2, of the photons emitted in this process is ______.
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)
What is the energy associated with first orbit of Li2+ (RH = 2.18 × 10-18)?
A 20% efficient bulb emits light of wavelength 4000 Å. If the power of the bulb is 1 W, the number of photons emitted per second is ______.
[Take, h = 6.6 × 10-34 J-s]
The figure below is the Energy level diagram for the Hydrogen atom. Study the transitions shown and answer the following question:
- State the type of spectrum obtained.
- Name the series of spectrum obtained.
