JEE Dual Nature of Matter & Radiation PYQs with Solutions PDF

A light wave described by $$E=60[\sin(3\times10^{15})t+\sin(12\times10^{15})t]$$ (in SI units) falls on a metal surface of work function 2.8 eV. The maximum kinetic energy of ejected photoelectron is (approximately) ___ eV. $$(h=6.6\times10^{-34}J.s\text{ and }e=1.6\times10^{19}C)$$

If an alpha particle with energy 7.7 MeV is bombarded on a thin gold foil, the closest distance from nucleus it can reach is ___ m. (Atomic number of gold = 79 and $$\frac{1}{4\pi\epsilon _{0}}=9\times10^{9} \text{in SI units} )$$

Light is incident on a metallic plate having work function $$110 \times 10^{-20}J$$. If the produced photoelectrons have zero kinetic energy then the angular frequency of the incident light is ___ rad/s. (h = $$6.63 \times 10^{-34}J.s.$$).

When a light of a given wavelength falls on a metallic surface the stopping potential for photoelectrons is 3.2 V. If a second light having wavelength twice of first light is used, the stopping potential drops to 0. 7 V. The wavelength of first light is ___ m.
$$(h= 6.63\times10^{-34}J.s,e=1.6\times10^{-19}C,c=3\times10^{8}m/s)$$

Number of photons of equal energy emitted per second by a 6 mW laser source operating at 663 nm is ____ . (Given: $$h=6.63\times 10^{-34}J.s\text{ and }c=3\times 10^{8} m/s$$)

light source of wavelength $$\lambda$$ illuminates a metal surface and electrons are ejected with maximum kinetic energy of 2 eV . If the same surface is illuminated by a light source of wavelength $$\frac{\lambda}{2}$$, then the maximum kinetic energy of ejected electrons will be (The work function of metal is 1 eV )

The work functions of cesium (Cs) and lithium (Li) metals are 1.9 eV and 2.5 eV , respectively. If we incident a light of wavelength 550 nm on these two metal surfaces, then photo-electric effect is possible for the case of

Two spherical bodies of same materials having radii 0.2 m and 0.8 m are placed in same atmosphere. The temperature of the smaller body is 800 K and temperature of the bigger body is 400 K . If the energy radiated from the smaller body is E, the energy radiated from the bigger body is (assume, effect of the surrounding temperature to be negligible),

In photoelectric effect an em-wave is incident on a metal surface and electrons are ejected from the surface. If the work function of the metal is 2.14 eV and stopping potential is 2 V , what is the wavelength of the emwave ? (Given hc = 1242eVnm where h is the Planck's constant and c is the speed of light in vaccum.)

In photoelectric effect, the stopping potential $$ (V_0)$$ $$v/s$$ frequency  $$(\nu)$$ curve is plotted. ( $$h$$ is Planck's constant and  $$\phi_0$$  is work function of the metal) $$(A)  V_0$$  $$v/s  \nu$$  is linear. $$(B)$$ } The slope of } $$V_0$$  $$v/s  \nu$$ $$\text{ curve } = \frac{\phi_0}{h}\text{ (C) } h \text{ constant is related to the slope of the}$$  $$V_0$$  v/s  $$\nu $$ line.(D) The value of electric charge of electron is not required to determine  $$h$$ using the  $$V_0$$ v/s  $$\nu$$  curve. $$(E)$$ The work function can be estimated without knowing the value of  h.Choose the correct answer from the options given below:

The ratio of the power of a light source  $$S_1$$ to that of the light source $$S_2$$ is  2.$$S_1$$ is emitting  $$2\times10^{15}$$ photons per second at  600,nm. If the wavelength of the source  $$S_2$$  is  300, nm,then the number of photons per second emitted by  $$S_2$$ is $$\underline {\hspace{2cm}}$$ $$\times 10^{14}.$$

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Emission of electrons in photoelectric effect can be suppressed by applying a sufficiently negative electron potential to the photoemissive substance. Reason (R) : A negative electric potential, which stops the emission of electrons from the surface of a photoemissive substance, varies linearly with frequency of incident radiation. In the light of the above statements, choose the most appropriate answer from the options given below :

A sub-atomic particle of mass $$10^{-30}$$kg is moving with a velocity $$2.21\times10^{6}$$ m/s . Under the matter wave consideration, the particle will behave closely like
$$\left(h=6.63\times10^{-34}J.s\right)$$

The de Broglie wavelengths of a proton and an $$\alpha$$ particle are $$\lambda$$ and $$2\lambda$$ respectively. The ratio of the velocities of proton and $$\alpha$$ particle will be :

Monochromatic light of frequency $$6 \times 10^{14}$$ Hz is produced by a laser. The power emitted is $$2 \times 10^{-3}$$ W. How many photons per second on an average, are emitted by the source? (Given $$h = 6.63 \times 10^{-34}$$ J s)

A convex lens of focal length $$40$$ cm forms an image of an extended source of light on a photoelectric cell. A current $$I$$ is produced. The lens is replaced by another convex lens having the same diameter but focal length $$20$$ cm. The photoelectric current now is

The threshold frequency of a metal with work function 6.63 eV is :

The de-Broglie wavelength of an electron is the same as that of a photon. If velocity of electron is $$25\%$$ of the velocity of light, then the ratio of K.E. of electron and K.E. of photon will be:

Two sources of light emit with a power of $$200$$ W. The ratio of number of photons of visible light emitted by each source having wavelengths $$300$$ nm and $$500$$ nm respectively, will be:

The work function of a substance is $$3.0 \text{ eV}$$. The longest wavelength of light that can cause the emission of photoelectrons from this substance is approximately:

For the photoelectric effect, the maximum kinetic energy $$E_k$$ of the photoelectrons is plotted against the frequency $$(\nu)$$ of the incident photons as shown in figure. The slope of the graph give

When a metal surface is illuminated by light of wavelength $$\lambda$$, the stopping potential is $$8$$ V. When the same surface is illuminated by light of wavelength $$3\lambda$$, stopping potential is $$2$$ V. The threshold wavelength for this surface is :

In a photoelectric effect experiment a light of frequency 1.5 times the threshold frequency is made to fall on the surface of photosensitive material. Now if the frequency is halved and intensity is doubled, the number of photo electrons emitted will be:

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Number of photons increases with increase in frequency of light. Reason R: Maximum kinetic energy of emitted electrons increases with the frequency of incident radiation. In the light of the above statements, choose the most appropriate answer from the options given below:

Which of the following statement is not true about stopping potential $$(V_0)$$ ?

In photoelectric experiment energy of $$2.48 \text{ eV}$$ irradiates a photo sensitive material. The stopping potential was measured to be $$0.5 \text{ V}$$. Work function of the photo sensitive material is :

Which of the following phenomena does not explain by wave nature of light. A. reflection B. diffraction C. photoelectric effect D. interference E. polarization. Choose the most appropriate answer from the options given below:

A proton and an electron have the same de Broglie wavelength. If $$K_p$$ and $$K_e$$ be the kinetic energies of proton and electron respectively, then choose the correct relation :

UV light of $$4.13 \text{ eV}$$ is incident on a photosensitive metal surface having work function $$3.13 \text{ eV}$$. The maximum kinetic energy of ejected photoelectrons will be:

A proton moving with one tenth of velocity of light has a certain de Broglie wavelength of $$\lambda$$. An alpha particle having certain kinetic energy has the same de-Broglie wavelength $$\lambda$$. The ratio of kinetic energy of proton and that of alpha particle is :