Competitive Exams: Physics MCQs (Practice-Test 24 of 35)

  1. Match List I with List II and select the correct answer.

    List-I (Physical constants) List-II (Formulae)
    1. Bohr radius

    2. Compton wavelength

    3. Bohr magnetron

    4. Fine structure constant

    1. ke2/hc

    2. h/mc

    3. eh/2m

    4. h/mke2

    • A
    • B
    • C
    • D
      • 1
      • 2
      • 3
      • 4
      • 4
      • 2
      • 3
      • 1
      • 2
      • 4
      • 1
      • 3
      • 4
      • 3
      • 2
      • 1
  2. If the frequency of Ka X-ray emitted from the element with atomic number 31 is f, then the frequency of Ka X-ray emitted from the element with atomic number 51 would be

    1. 5/3 f

    2. 51/31 f

    3. 25/9 f

    4. 9/25 f

  3. If the magnetic quantum number m1 of an electron in a particular excited state of hydrogen atom is 5, then the possible choice of quantum numbers n, l, m1and ms would be respectively

    1. 8, 6, 5, ½

    2. 6, 6, 5-½

    3. 7, 7, 5, ½

    4. 5, 5, 5-½

  4. According to Pauli principle 2n2 electron can occupy the major shell with principal quantum number n. Out of 50 electrons in the major shell n = 5, the number of electrons having magnetic quantum number m1 = 1 would be

    1. 5

    2. 10

    3. 8

    4. 2

  5. Given that the formula for the various spectral series in the hydrogen atom is given by 1/l = R (1/n2 − 1/n2) where n1 and n integers, match List I and List II and select the correct answer using the codes given below the lists:

    List-I (Values of n1) List-II
    1. Balmer series

    2. Brackett series

    3. Paschel series

    4. Lyman series

    1. n1 = 1

    2. n1 = 2

    3. n1 = 3

    4. n1 = 4

    • A
    • B
    • C
    • D
      • 2
      • 1
      • 3
      • 4
      • 2
      • 4
      • 3
      • 1
      • 3
      • 4
      • 1
      • 2
      • 4
      • 3
      • 2
      • 1
  6. Which one of the following pairs of phenomena illustrates the particular aspect of wave-particle duality?

    1. Compton effect and Bragg's law

    2. Photoelectric effect and Compton effect

    3. Compton effect and Pauli principle

    4. Bragg's law and photoelectric effect

  7. Consider the following statements regarding compton effect:

    1. Wavelength of scattered photon is greater than the wavelength of incident photon.

    2. For scattering angle equal to 900 the change in wavelength of the scattered photon (known as Compton shift) is constant

    3. The maximum Compton shift occurs when the scattering angle is 1800

    4. Compton shift depends upon the wavelength of the incident photon.

    5. Compton shift depends upon! he nature of the scattering material.

    Of these statements:

    1. 1, 2 and 3 are correct

    2. 2, 4 and 5 are correct

    3. 3, 4 and 5 are correct

    4. 1, 4 and 5 are correct

  8. An electron of in mass ‘m’ and change ‘e’ initially at rest gets accelerated by a constant electric field E. The rate of change of de-Broglie wavelength of this electron at time t, ignoring relativistic effects, is

    1. -h/e E t2

    2. -e h t/E

    3. -m h/e E t2

    4. -h/e E

  9. If a nucleus A/Z X emits an alpha particle and a beta particle, then the daughter nucleus Will have which of the following configurations?

    1. A − 4 nucleons

    2. Z − 2 protons

    3. A-Z − 3 neutrons

    Select the correct answer using the codes given below:

    1. 1, 2 and 3

    2. 1 and 2

    3. 1 and 3

    4. 2 and 3

  10. Which one of the following statements about uranium is correct?

    1. 235U us fissionable by thermal neutrons

    2. Fast neutrons trigger the fission process in 235U

    3. 238U breaks up into fragments, when bombarded by slow neutrons

    4. 235U is an unstable isotope and undergoes spontaneous fission

  11. Consider the following statements regarding classification of elementary particles:

    1. m, h K are called leptons.

    2. p, hare called nucleons.

    3. A, X, W are caned hyperons.

    Of these statements

    1. 1, 2 and 3 are correct

    2. 1 alone is correct

    3. 2 and 3 are correct

    4. 1 and 3 are correct

  12. Match List I and List II and select the correct answer.

    List-I (Types of interactions) List-II (Field quanta)
    1. Strong

    2. Electromagnetic

    3. Weak

    4. Gravitational

    1. Graviton

    2. Photon

    3. Intermediate vector Boson

    4. Pion

    • A
    • B
    • C
    • D
      • 4
      • 3
      • 1
      • 2
      • 1
      • 2
      • 3
      • 4
      • 4
      • 2
      • 3
      • 1
      • 3
      • 4
      • 2
      • 1
  13. In a vacuum diode, the plate current l varies with plate voltage V as

    1. V1/2

    2. V

    3. V3/2

    4. V2

  14. When the plate voltage of a triode is increased from 225 V to 260 V, the control grid voltage must be changed from-4 V to-4.7 V to keep the plate current constant. The amplification factor m of the triode is:

    1. 70

    2. 50

    3. 35

    4. 15

  15. The mutual characteristics of the triode is a relation between

    1. plate voltage and plate current

    2. plate voltage and grid current

    3. grid voltage and plate voltage

    4. grid voltage and plate current