raghu Katagall
Quiz by , created over 1 year ago

Quiz on Physics, created by raghu Katagall on 09/11/2017.

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raghu Katagall
Created by raghu Katagall over 1 year ago
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Question 1

Question
In the Bohr model of the hydrogen atom, let R, V and E represent the radius of the orbit, the speed of electron and the total energy of the electron respectively. Which of the following quantity is proportional to the quantum number n?
Answer
  • VR
  • RE
  • E/V
  • R/E

Question 2

Question
The work function for aluminium is 4.125 eV. The cut off wavelength for photoelectric effect for Aluminium is
Answer
  • 200 nm
  • 300 nm
  • 150 nm
  • 420 nm

Question 3

Question
The electron is a hydrogen atom makes a transition from n = n1 to n = n2 state. The time period of the electron in the final state is eight times that in the initia state. Then the possible values of n1 and n2 are
Answer
  • n1 = 8, n2 = 2
  • n1 = 4, n2 = 2
  • n1 = 6, n2 = 2
  • n1 = 1, n2 = 2

Question 4

Question
Light of frequency 1.5 times the threshold frequency is incident on photosensitive material. If the frequency is halved and intensity is doubled, the photocurrent becomes
Answer
  • Quadrupled
  • Doubled
  • Zero
  • Halved

Question 5

Question
A radioactive substance has a half life of four months. Three fourth of the substance will decay in
Answer
  • 12 months
  • 4 months
  • 8 months
  • 3 months

Question 6

Question
A radio isotope has a half life of 5 years. The fraction of the atoms of this material that would decay in 15 years will be
Answer
  • 1
  • 2/3
  • 7/8
  • 5/8

Question 7

Question
When Boron 5B10 is bombarded by neutron,  particles are emitted. The resulting nucleus has mass number
Answer
  • 11
  • 6
  • 7
  • 15

Question 8

Question
Tracer techniques make use of
Answer
  • neutron scattering
  • electron beams
  • lasers
  • radioactive isotopes

Question 9

Question
A sample of radioactive substance contains 2,828 atoms. If its half life is two days, how many atoms will be left intact in the sample after one day?
Answer
  • 2,000
  • 1,000
  • 1,414
  • 707

Question 10

Question
The unit of Planck’s constant is
Answer
  • Nm
  • eV
  • Js–1
  • Js

Question 11

Question
Mean life of a radioactive element is one year. Then its half life is (years)
Answer
  • 0.5
  • 0.4
  • 1
  • 0.693

Question 12

Question
Hydrogen atom emits blue light when it jumps from n = 4 energy level to the n = 2 energy level. Which colour of light would the atom emit when it jumps from the n = 5 level to the n = 2 level?
Answer
  • Red
  • Yellow
  • Green
  • Violet

Question 13

Question
The electromagnetic theory of light was developed by
Answer
  • Max Planck
  • Maxwall
  • Newton
  • Huygens

Question 14

Question
The concept of quantum nature of light has emerged in an attempt to explain
Answer
  • black – body radiation
  • photoelectric effect
  • polarisation of light
  • interference and diffraction.

Question 15

Question
The electron in the innermost orbit of an atom has _____ velocity.
Answer
  • mean
  • zero
  • highest
  • lowest

Question 16

Question
Einstein’s photoelectric equation was experimentally verified by
Answer
  • Millikan
  • Rutherford
  • Einstein
  • Fermi
  • all the above

Question 17

Question
A photon of energy 8 eV is incident on a metal surface of threshold frequency 1.6  1015 Hz. The K.E of the photoelectrons emitted (in eV) (Take h = 6  10–34 Js)
Answer
  • 2
  • 1.2
  • 1.6
  • 6

Question 18

Question
TV waves have a wavelength range of 1-10 metre. This frequency range in MHz is
Answer
  • 3 – 3000
  • 300 – 3000
  • 3 – 30
  • 30 – 300

Question 19

Question
. An electron and a proton have the same de-Broglie wavelength. Then the kinetic energy of the electron is
Answer
  • greater than the kinetic energy of the proton
  • zero
  • Infinity
  • equal to the kinetic energy of the proton

Question 20

Question
Whenever a hydrogen atom emits a photon in the Balmer series
Answer
  • It may emit another photon in the Balmer series
  • It must emit another photon in the Lyman series
  • It may emit another photon in the Paschen series
  • It need not emit any more photon

Question 21

Question
The de Broglie wavelength of an electron in the first Bohr orbit is
Answer
  • equal to the circumference of the first orbit
  • equal to twice the circumference of the first orbit
  • equal to half the circumference of the first orbit
  • equal to one fourth the circumference of the first orbit