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

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raghu Katagall
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Physics

Physics

Question 1 of 21

1

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?

Select one of the following:

  • VR

  • RE

  • E/V

  • R/E

Explanation

Question 2 of 21

1

The work function for aluminium is 4.125 eV. The cut off wavelength for photoelectric effect for Aluminium is

Select one of the following:

  • 200 nm

  • 300 nm

  • 150 nm

  • 420 nm

Explanation

Question 3 of 21

1

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

Select one of the following:

  • n1 = 8, n2 = 2

  • n1 = 4, n2 = 2

  • n1 = 6, n2 = 2

  • n1 = 1, n2 = 2

Explanation

Question 4 of 21

1

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

Select one of the following:

  • Quadrupled

  • Doubled

  • Zero

  • Halved

Explanation

Question 5 of 21

1

A radioactive substance has a half life of four months. Three fourth of the substance will decay in

Select one of the following:

  • 12 months

  • 4 months

  • 8 months

  • 3 months

Explanation

Question 6 of 21

1

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

Select one of the following:

  • 1

  • 2/3

  • 7/8

  • 5/8

Explanation

Question 7 of 21

1

When Boron 5B10 is bombarded by neutron,  particles are emitted. The resulting nucleus has mass number

Select one of the following:

  • 11

  • 6

  • 7

  • 15

Explanation

Question 8 of 21

1

Tracer techniques make use of

Select one of the following:

  • neutron scattering

  • electron beams

  • lasers

  • radioactive isotopes

Explanation

Question 9 of 21

1

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?

Select one of the following:

  • 2,000

  • 1,000

  • 1,414

  • 707

Explanation

Question 10 of 21

1

The unit of Planck’s constant is

Select one of the following:

  • Nm

  • eV

  • Js–1

  • Js

Explanation

Question 11 of 21

1

Mean life of a radioactive element is one year. Then its half life is (years)

Select one of the following:

  • 0.5

  • 0.4

  • 1

  • 0.693

Explanation

Question 12 of 21

1

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?

Select one of the following:

  • Red

  • Yellow

  • Green

  • Violet

Explanation

Question 13 of 21

1

The electromagnetic theory of light was developed by

Select one of the following:

  • Max Planck

  • Maxwall

  • Newton

  • Huygens

Explanation

Question 14 of 21

1

The concept of quantum nature of light has emerged in an attempt to explain

Select one of the following:

  • black – body radiation

  • photoelectric effect

  • polarisation of light

  • interference and diffraction.

Explanation

Question 15 of 21

1

The electron in the innermost orbit of an atom has _____ velocity.

Select one of the following:

  • mean

  • zero

  • highest

  • lowest

Explanation

Question 16 of 21

1

Einstein’s photoelectric equation was experimentally verified by

Select one of the following:

  • Millikan

  • Rutherford

  • Einstein

  • Fermi

  • all the above

Explanation

Question 17 of 21

1

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)

Select one of the following:

  • 2

  • 1.2

  • 1.6

  • 6

Explanation

Question 18 of 21

1

TV waves have a wavelength range of 1-10 metre. This frequency range in MHz is

Select one of the following:

  • 3 – 3000

  • 300 – 3000

  • 3 – 30

  • 30 – 300

Explanation

Question 19 of 21

1

. An electron and a proton have the same de-Broglie wavelength. Then the kinetic energy of the electron is

Select one of the following:

  • greater than the kinetic energy of the proton

  • zero

  • Infinity

  • equal to the kinetic energy of the proton

Explanation

Question 20 of 21

1

Whenever a hydrogen atom emits a photon in the Balmer series

Select one of the following:

  • 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

Explanation

Question 21 of 21

1

The de Broglie wavelength of an electron in the first Bohr orbit is

Select one of the following:

  • 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

Explanation

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