Momentum
FACT/DEFINITION TYPE QUESTIONS
Q.
e angular momentum of the electron in hydrogen atom in the ground state is
(c) According to Bohr's theory, Angular momentum,
So in ground state, angular momentum = h/2pie
Q.
According to Bohr’s model of hydrogen atom (a) the linear velocity of the electron is quantised. (b) the angular velocity of the electron is quantised. (c) the linear momentum of the electron is quantised. (d) the angular momentum of the electron is quantised.
d
Q.
Which of the following parameters is the same for all hydrogen-like atoms and ions in their ground states? (a) Radius of the orbit (b) Speed of the electron (c) Energy of the atom (d) Orbital angular momentum of the electron
(d) The orbital angular momentum of electron is independent of mass of orbiting particle & mass of nuclei.
Q.
Particle like behavior of light arises from the fact that each quanta of light has definite ...X... and a fixed value of ...Y.. just like a particle, Here, X and Y refer to
a) frequency, energy
(b) shape, volume
(c) energy, frequency
(d) energy, moment
(d) Einstein arrived at the important result that the light quantum can also be associated with momentum hv/c A definite value of energy as well as momentum is a strong sign that the light quantum can be associated with a particle. This particle was later named photon.
Q.
In a photon-particle collision, the quantity that does not remain conserved is (a) total energy (b) total momentum (c) number of photons (d) None of these
(c) In a photon – particle collision, the number of photons may not be conserved. The photon may be absorbed or a new photon may be created.
Q.
Of the following properties, the photon does not possess (a) rest mass(b) momentum (c) energy(d) frequency
Of the following properties, the photon does not possess (a) rest mass(b) momentum (c) energy(d) frequency
Q.
The momentum of a photon of wavelength lemda is ( a )h lemda (b) h/lemda (c) lemda/h
b
Q.
The photoelectric effect is based on the law of conservation of (a) momentum (b) energy (c) angular momentum (d) mass
(b) Photoelectric effect is based on law of conservation of energy
Q.
According to Heisenberg’s uncertainty principle, it is true that (a) we can precisely specify the momentum and energy of an electron (b) we cannot precisely specify the momentum and wavelength associated with an electron. (c) we cannot precisely specify the momentum and position of electron at the same time. (d) we can precisely specify the momentum and position of electron at the same time.
c
Q.
Which of the following statements are true?
I. In the interaction with matter, radiation behaves as if it is made up of particle called photons.
II. Each photon has energy E = hv and momentum P = hv/c.
III. photons are electrically neutral and are not deflected by electric and magnetic field.
IV. In a photon particle collision, photon number is conserved.
(a) I and II
(b) I, II and III
(c) I, III and IV
(d) I, II and IV
(b)
(i) In interaction of radiation with matter, radiation behaves as if it is made up of particles called photons.
(ii) Each photon has energy E (= hv) and momentum p (= h v/c) and speed c, the speed of light.
(iii) All photons of light of a particular frequency v, or wavelength lemda have the same energy, E (= hv = hc/lemda) and momentum P(=hv/c=h/lemda), whatever the intensity of radiation may be. By increasing the intensity of light of given wavelength, there is only an increase in the number of photons per second crossing a given area, with each photon having the same energy. Thus, photon energy is independent of intensity of radiation.
(iv) Photons are electrically neutral and are not deflected by electric and magnetic fields.
(v) In photon-particle collision (such as photoelectron collision), the total energy and total momentum are conserved. however, the number of photons may not be conserved in a collision. The photon may be absorbed or a new photon may be created
Q.
Assertion : The photon behaves like a particle.
Reason : If E and P are the energy and momentum of the photon, then
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct
a
Q.
Assertion : In an experiment on photoelectric effect, a photon is incident on an electron from one direction and the phtoelectron is emitted almost in the opposite direction. It violate the principle of conservation of linear momentum. Reason :It does not violate the principle of conservation of linear momentum.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct
d
Q.
Assertion : Two photons of equal wavelength must have equal linear momentum.
Reason : Two photons of equal linear momentum will have equal wavelength
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct
(d) To photons of equal wavelength will have equal momentum (magnitude), but direction of momentum may be different.
CRITICAL THINKING TYPE QUESTIONS
Q.
If the momentum of electron is changed by P, then the de Broglie wavelength associated with it changes by 0.5%. The initial momentum of electron will be (a) 200 P (b) 400 P (c)P/ 200 d) 100 P
Q.
If the energy of a photon is 10 eV, then its momentum is
