## Class 12 Physics MCQs Dual Nature Of Radiation for JEE/NEET

Here, you will get Class 12 Physics MCQ of Chapter 11 Dual Nature Of Radiation for cracking JEE and NEET/AIIMS. By solving these MCQs of Class 12 Physics Chapter 11 Dual Nature Of Radiation, you will get the confidence to crack JEE or NEET. Practice MCQ Questions for Class 12 Physics with Answers on a daily basis and score well in exams.

With which of the following particles moving with same velocity de-Broglie wave length will be maximum?
(a) ß-particle
(b) ∝ particle
(c) electron
(d) proton

A metal surface ejects electrons when hit by green light but nothing when hit by yellow light. The electrons will be ejected when the surface is hit by
(a) blue light
(b) heat rays
(c) infrared light
(d) red light

The maximum value of photoelectric current is called
(a) base current
(b) saturation current
(c) collector current
(d) emitter current

When an electron jumps across a potential difference of 1 V, it gains energy equal to
(a) 1.602 × 10-19 J
(b) 1.602 × 1019 J
(c) 1.602 × 1024 J
(d) 1 J

Answer: (a) 1.602 × 10-19 J

The time required in emitting photo electrons is
(a) 10-8 s
(b) 10-4 s
(c) Zero
(d) 1 sec

The photoelectric effect can be explained by
(a) Corpuscular theory of light
(b) Wave nature of light
(c) Bohr’s theory
(d) Quantum theory of light

Answer: (d) Quantum theory of light

A proton, a neutron, an electron and an a-particle have same energy. Then their de Broglie wavelengths compare as
(a) λp = λn > λe > λα
(b) λα < λp = λn < λe
(c) λe < λp = λn > λα
(d) λe = λp = λn = λα

Answer: (b) λα < λp = λn < λe

Who established that electric charge is quantised?
(a) J.J. Thomson
(b) William Crookes
(c) R.A. Millikan
(d) Wilhelm Rontgen

Compared to liquids and solids, gases are
(a) good conductors of electricity
(b) best conductors of electricity
(c) very poor conductors of electricity
(d) good or bad conductors of electricity depending upon the nature of the gas

Answer: (c) very poor conductors of electricity

What is the de-Broglie wavelength of an electron accelerated from rest through a potential difference of 100 volts?
(a) 12.3 Å
(b) 1.23 Å
(c) 0.123 Å
(d) None of these

Work function of three metals A, B and C are 4.5 eV, 4.3 eV and 3.5 eV respectively. If a light of wavelength 4000 Å is incident on the metals then
(a) photoelectrons are emitted from A.
(b) photoelectrons are emitted from B.
(c) photoelectrons are emitted from C.
(d) photoelectrons are emitted from all the metals.

Answer: (d) photoelectrons are emitted from all the metals

The wavelength associated with n electron is 1Å. The potential difference required for accelerating it is
(a) 100 V
(b) 150 V
(c) 250 V
(d) 10³ V

Ultra-violet radiation of 6.2 eV falls on an aluminium surface having work-function 4.2 eV. The kinetic energy (in J) of the fastest electron emitted is nearly.
(a) 3 × 10-19
(b) 3 × 10-15
(c) 3 × 10-17
(d) 3 × 10-21

A photocell is illuminated by a small bright source placed 1 metre away. When the same source of light is placed 2 m away, the electrons emitted per sec. (i.e. saturation current in the photo cell is) are
(a) I ∝ 2²
(b) I × 1/4
(c) I ∝ 4
(d) I ∝ 1/2

The frequency and the intensity of a beam of light falling on the surface of photoelectric material are increased by a factor of two. This will
(a) increase the maximum K.E. of photo-electron as well as photoelectric current by a factor of two.
(b) increase maximum K.E. of photoelectrons and would increase the photo current by a factor of two.
(c) increase the maximum K.E. of photo electrons by a factor of two and will no affect photoelectric current.
(d) No effect on both maximum K.E. and photoelectric current

Answer: (b) increase maximum K.E. of photoelectrons and would increase the photo current by a factor of two

An electron accelerated through a potential difference of V volt has a wavelength λ associated with it, Mass of proton is nearly 2000 times that of an electron. In order to have the same λ for proton, it must be accelerated through a potential difference (in volt) of
(a) V
(b) √2000V
(c) 2000V
(d) V/2000

The de-Broglie wavelength of an electron moving with a speed of 6.6 × 1015 ms-1 is nearly equal to
(a) 10-11m
(b) 10-9 m
(c) 10-7 m
(d) 10-5 m

X-rays are
(a) deflected by an electric field
(b) deflected by a magnetic field
(c) deflected by both electric and magnetic fields
(d) not deflected by electric and magnetic fields

Answer: (d) not deflected by electric and magnetic fields

Name the scientists who first studied the passage of electricity through fluids to establish the electrical nature of matter
(a)Millikan
(b) Planck
(d) Boyle

The work function of photoelectric material is 3.3 eV. The threshold frequency will be equal to
(a) 8 × 1014 Hz
(b) 8 × 1010 Hz
(c) 5 × 1010 Hz
(d) 4 × 1014 Hz

Answer: (a) 8 × 1014 Hz

The ratio of specific charge of an alpha particle to the proton is
(a) 1 : 2
(b) 2 : 1
(c) 4 : 1
(d) 1 : 4

Protons and alpha particles have the same de-Broglie wavelength. What is same for both of them ?
(a) Energy
(b) Time period
(c) Frequency
(d) Momentum

Radiations of frequency v are incident on a photosensitive metal. The maximum K.E. of the photoelectrons is E. When the frequency of the incident radiation is doubled, what is the maximum kinetic energy of the photoelectrons?
(a) 2E
(b) 4E
(c) E + hv
(d) E – hv

Light of frequency 1.9 times the threshold frequency is incident on a photosensitive material. If the frequency is halved and intensity is doubled, the photocurrent becomes
(b) doubled
(c) halved
(d) zero