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# 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1

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## 35 Questions MCQ Test Physics Class 12 | 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 for NEET 2023 is part of Physics Class 12 preparation. The 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 questions and answers have been prepared according to the NEET exam syllabus.The 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 MCQs are made for NEET 2023 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 below.
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31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 1

### Which one of the following statements is nottrue for cathode rays?      [2002]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 1

Cathode rays are negatively charged rays.
Hence, when electric field is applied to them,
then they deflect in direction opposite to
electric field.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 2

### When ultraviolet radiation is incident on asurface, no photoelectrons are emitted. If asecond beam causes photoelectrons to beejected, it may consists of    [2002]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 2

Energy of photon of X-rays is more than
energy of photon of ultraviolet rays. Because
frequency of X rays is more than ultraviolet
rays.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 3

### A photoelectric cell is illuminated by a pointsource of light 1m away. When the source isshifted to 2m then [2003]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 3

Power ∝ No. of electrons emitted (N)

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 4

According to Einstein’s photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 4

K.E. = hν – φ
∴ graph of K.E. versus ν is a straight line
with +ve slope h and K.E. > 0 for ν such that
hν > φ.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 5

A photosensitive metallic surface has workfunction, hv0. If photons of energy 2 hv0 fallon this surface, the electrons come out with amaximum velocity of 4 ×106 m/s. When thephoton energy is increased to 5 hv0, thenmaximum velocity of photoelectrons will be

[2005]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 5

We know that

According to question

v2 = 2v1 = 2 × 4× 106 = 8 × 106 m/s.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 6

The work functions for metals A, B and C arerespectively 1.92 eV, 2.0 eV and 5 eV.According to Einstein s equation, the metalswhich will emit photoelectrons for a radiationof wavelength 4100 Å is/are [2005]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 6

So, only metals having work function less
than 3eV can emit photoelectrons for the

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 7

When photons of energy hv fall on an aluminiumplate (of work function E0), photoelectrons ofmaximum kinetic energy K are ejected. If thefrequency of the radiation is doubled, themaximum kinetic energy of the ejectedphotoelectrons will be     [2006]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 7

Applying Einstein's formula for photoelectricity

If we use 2v frequency then let the kinetic
energy becomes K'
So,

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 8

In a discharge tube ionization of enclosed gas isproduced due to collisions between [2006]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 8

When electrons emitted from cathode collide
with gas molecules or atoms, they knock out
outer electrons and produce positively
charged ions. They become part of positive
rays.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 9

A photo-cell employs photoelectric effect toconvert      [2006]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 9

A photo-cell employs photoelectric effect to
convert light energy into photoelectric
current.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 10

The momentum of a photon of energy 1 MeV inkg m/s, will be [2006]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 10

1 MeV = 106 × 1.6 × 10–19 joule
Momentum of photon

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 11

Monochromatic light of frequency 6.0 × 1014 Hzis produced by a laser. The power emitted is 2 × 10–3 ω. The number of photons emitted, onthe average, by the sources per second is            [2007]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 11

Since p = nhv

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 12

A 5 watt source emits monochromatic light ofwavelength 5000 Å. When placed 0.5 m away, itliberates photoelectrons from a photosensitivemetallic surface. When the source is moved to adistance of 1.0 m, the number of photoelectronsliberated will be reduced by a factor of [2007]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 12

Therefore, as distance is doubled, NE
decreases by (1/4) times.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 13

The work function of a surface of aphotosensitive material is 6.2 eV. The wavelengthof incident radiation for which the stoppingpotential is 5 V lies in the: [2008]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 13

Work function, φ0 = 6.2eV.
Stopping potential V0 = 5V.

Thus the wavelength of the incident radiation
lies in the ultraviolet region.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 14

In the phenomenon of electric discharge throughgases at low pressure, the coloured glow in thetube appears as a result of: [2008]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 14

The coloured glow in the tube appears as a
result of excitations of electrons in the
atoms.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 15

A particle of mass 1 mg has the same wavelengthas an electron moving with a velocity of 3×10ms–1. The velocity of the particle is:    [2008]
(mass of electron = 9.1×10–31 kg)

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 15

Wavelength of

where v is the velocity of the particle.
Wave length of electron

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 16

The number of photo electrons emitted for lightof a frequency v (higher than the threshold frequency v0) is proportional to: [2009]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 16

The number of photoelectrons emitted is
proportional to the intensity of incident
light. Saturation current  ∝ intensity.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 17

The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement? [2009]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 17

Retarding potential depends on the
frequency of incident radiation but is
independent of intensity.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 18

Monochromatic light of wavelength 667 nm isproduced by a helium neon laser. The poweremitted is 9 mW. The number of photons arrivingper sec on the average at a target irradiated bythis beam is: [2009]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 18

λ = 667 × 10–9m, P = 9 ×10–3W

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 19

A beam of cathode rays is subjected to crossed Electric (E) and Magnetic fields (B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by: [2010]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 19

For no deflection of beam, eE = evB

⇒ v = E/B

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 20

A source S1 is producing, 1015 photons persecond of wavelength 5000 Å. Another source S2 is producing 1.02×1015 photons per secondof wavelength 5100Å Then, (power of S2) (power of S1) is equal to : [2010]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 20

Energy emitted/sec by

Energy emitted/sec by

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 21

The potential difference that must be applied tostop the fastest photoelectrons emitted by anickel surface, having work function 5.01 eV,when ultraviolet light of 200 nm falls on it, mustbe:  [2010]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 21

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 22

Photoelectric emmision occurs only whenthe incident light has more than a certainminimum [2011]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 22

For occurence of photoelectric effect, the
incident light should have frequency more
than a certain minimum which is called the
threshold frequency (v0).

For photoelectric effect emission v > v0
where v is the frequency of the incident
light.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 23

In the Davisson and Germer experiment, thevelocity of electrons emitted from the electrongun can be increased by [2011]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 23

In the Davisson and Germer experiment, the
velocity of electrons emitted from the
electron gun can be increased by
increasing the potential difference between
the anode and filament.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 24

Light of two different frequencies whosephotons have energies 1 eV and 2.5 eVrespectively illuminate a metallic surface whosework function is 0.5 eV successively. Ratioof maximum speeds of emitted electrons will be[2011]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 24

The maximum kinetic energy of emitted
electrons is given by

K.E = φ – φ0
K.E1 = 1 eV – 0.5 eV = 0.5 eV
K.E2 = 2.5 eV – 0.5 eV = 2 eV

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 25

Electrons used in an electron microscope areaccelerated by a voltage of 25 kV. If the voltageis increased to 100kV then the de–Brogliewavelength associated with the electrons would

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 25

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 26

In photoelectric emission process from a metalof work function 1.8 eV, the kinetic energy ofmost energetic electrons is 0.5 eV. Thecorresponding stopping potential is     [2011]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 26

The stopping potential is equal to maximum
kinetic energy.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 27

The threshold frequency for a photosensitivemetal is 3.3 × 1014 Hz. If light of frequency 8.2 × 1014 Hz is incident on this metal, the cut-offvoltage for the photoelectric emission is nearly   [2011M]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 27

K.E. = hv – hvth = eV0 (V0 = cut off voltage)

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 28

A 200 W sodium street lamp emits yellow lightof wavelength 0.6 μm. Assuming it to be 25%  efficient in converting electrical energy to light,the number of photons of yellow light it emitsper second is [2012]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 28

Give that, only 25% of 200W converter
electrical energy into light of yellow colour

Where N is the No. of photons emitted per
second, h = plank’s constant, c, speed of
light.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 29

Monochromatic radiation emitted when electronon hydrogen atom jumps from first excited tothe ground state irradiates a photosensitivematerial. The stopping potential is measured tobe 3.57 V. The threshold frequency of the materialsis : [2012]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 29

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 30

If the momentum of electron is changed by P,then the de Broglie wavelength associated withit changes by 0.5%. The initial momentum ofelectron will be : [2012M]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 30

The de-Broglie’s wavelength associated

with the moving electron

Now, according to problem

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 31

Two radiations of photons energies 1 eV and 2.5 eV, successively illuminate a photosensitivemetallic surface of work function 0.5 eV. The ratioof the maximum speeds of the emitted electronsis : [2012M]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 31

According to Einsten’s photoelectric effect,
the K.E. of the radiated electrons

K.Emax = E-W

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 32

For photoelectric emission from certain metal the cut-off frequency is v. If radiation of frequency 2v impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass) [NEET 2013

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 32

From photo-electric equation,

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 33

The wavelength λe of an electron and λp of a photon are of same energy E are related by   [NEET 2013]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 33

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 34

A source of light is placed at a distance of 50 cm from a photocell and the stopping potential is found to be V0. If the distance between the lightsource and photocell is made 25 cm, the newstopping potential will be [NEET Kar. 2013]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 34

Since, stopping potential is independent
of distance hence new stopping potential
will remain unchanged i.e., new stopping
potential = V0.

31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 35

The de-Broglie wavelength of neutron in thermal equilibrium at temperature T is       [NEET Kar. 2013]

Detailed Solution for 31 Year NEET Previous Year Questions: Dual Nature of Radiation & Matter - 1 - Question 35

From formula

[By placing value of h, m and k)

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