Download App

Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsDual Nature of Radiation and Matter4 Marks
Question

According to Einstein, when a photonoflight offrequencyu or wavelength $\lambda$ is incident on a photosensitive metal surface of work function $\phi_0$, where $\phi_0<\text{h}\upsilon$ (here, h is Planck's constant), then the emission of photoelectrons takes place. The maximum kinetic energy of the emitted photoelectrons is given by $\text{K}_\text{max}=\text{h}\upsilon-\phi_0$. If the frequency of the incident light is $\upsilon_0$ called thresold frequency, the photoelectrons are emitted from metal without any kinetic energy. So $\text{h}\upsilon_0=\phi_0$.

  1. A metal of work function 3.3eV is illuminated by light of wavelength 300nm. The maximum kinetic energy of photoelectrons emitted is (taking h = 6.6 × 10-34 Js).
  1. 0.413eV
  2. 0.825eV
  3. 1.65eV
  4. 1.32eV

  1. The variation of maximum kinetic energy (Kmax) of the variation of maximum kinetic energy ($\upsilon$) of the incident radiations can be represented by:

  1. The variation of photoelectric current (i) with the intensity of the incident radiation (I) can be represented by:

  1. The graph between the stopping potential (V0) and $\Big(\frac{1}{\lambda}\Big)$ is shown in the figure. $\phi_1,\phi_2,\phi_3$ are work function. Which of the following options is correct?

  1. $\phi_1:\phi_2:\phi_3=1:2:3$

  2. $\phi_1:\phi_2:\phi_3=4:2:1$

  3. $\phi_1:\phi_2:\phi_3=1:2:4$

  4. Ultraviolet tight can be used to emit photoelectrons from metal 2 and metal 3 only.
  1. Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?

✓

Answer

  1. (b) 0.825eV

Explanation:

$\text{K}_\text{max}=\text{h}\upsilon-\phi_0=\frac{\text{hc}}{\lambda}-\phi_0$

$=\frac{(6.6\times10^{-34})\times(3\times10^8)}{(300\times10^{-9})\times(1.6\times10^{-19})}-3.3$

$=4.125\times3.3=0.825\text{eV} $

  1.  

Explanation:

$\text{K}_\text{max}=\text{h}\upsilon-\phi_0$, when $\upsilon=\upsilon_0,\text{K}_\text{max}=0$

$\therefore0=\text{h}\upsilon_0$ or $\phi_0=\text{h}\upsilon_0$

If $\upsilon<\upsilon_0$, then Kmax is negative, i.e., no photoelectric emission takes place. Thus, graph (c) is possible.

  1.  

Explanation:

Photoelectric current (i) is proportional to the intensity of the emission light. Thus, graph (a) is possible.

  1. (c) $\phi_1:\phi_2:\phi_3=1:2:4$

Explanation:

From Einstein's photoelectric equation,

$\text{K}_\text{max}=\text{eV}_0=\frac{\text{hc}}{\lambda}-\phi$

or $\text{V}_0=\frac{\text{hc}}{\text{e}}\cdot\frac{1}{\lambda}-\frac{\phi}{\text{e}}$

Graph of V0 versus $\frac{1}{\lambda}$ s a straight line

Slope of straight line, $\tan\theta=\frac{\text{hc}}{\text{e}}$

At V0 = 0, we have

$\phi_1:\phi_2:\phi_3=\frac{\text{hc}}{\lambda_{01}}:\frac{\text{hc}}{\lambda_{02}}:\frac{\text{hc}}{\lambda_{03}}$

$0.001\text{hc}:0.002\text{hc}:0.004\text{hc}$

$\therefore1:2:4$

  1.  

Explanation:

de-Broglie wavelength

$\lambda=\frac{\text{h}}{\text{P}}\text{i.e.,}\lambda\propto\frac{1}{\text{P}}$

So the graph between $\lambda$ and p is of the type shown is option (d).

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "4 Marks Questions" from Dual Nature of Radiation and Matter→Dual Nature of Radiation and Matter — all question types→Physics STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

A solenoid 60 cm long and of radius 4.0 cm has 3 layers of windings of 300 turns each. A 2.0 cm long wire of mass 2.5 g lies inside the solenoid (near its centre) normal to its axis; both the wire and the axis of the solenoid are in the horizontal plane. The wire is connected through two leads parallel to the axis of the solenoid to an external battery which supplies a current of 6.0 A in the wire. What value of current (with appropriate sense of circulation) in the windings of the solenoid can support the weight of the wire? g = 9.8 m s–2.
→

The magnetic field lines of the earth resemble that of a hypothetical magnetic dipole located at the centre of the earth. The axis of the dipole is presently tilted by approximately 11.3° with respect to the axis of rotation of the earth.

The pole near the geographic North pole of the earth is called the North magnetic pole and the pole near the geographic South pole is called South magnetic pole.

  1. Magnetization of a sample is:
  1. 105T
  2. 10-6T
  3. 10-5T
  4. 108T
  1. A bar magnet is placed North-South with its North-pole due North. The points of zero magnetic field will be in which direction from centre of magnet?
  1. North-South
  2. East- West
  3. North-East and South-West
  4. None of these.
  1. The value of angle of dip is zero at the magnetic equator because on it:
  1. V and Hare equal.
  2. The values of V and H zero.
  3. The value of V is zero.
  4. The value of His zero.
  1. The angle of dip at a certain place, where the horizontal and vertical components of the earth's magnetic field are equal, is:
  1. 30º
  2. 90º
  3. 60º
  4. 45º
  1. At a place, angle of dip is 300. lf horizontal component of earth's magnetic field is H, then the total intensity of magnetic field will be.

  1. $\frac{\text{H}}{2}$

  2. $\frac{2\text{H}}{\sqrt{3}}$

  3. $\text{H}\sqrt{\frac{3}{2}}$

  4. $2\text{H}$

→

To study photoelectric effect, an emitting electrode C of a photosensitive material is kept at negative potential and collecting electrode A is kept at positive potential in an evacuated tube. When light of sufficiently high frequency falls on emitting electrode, photoelectrons are emitted which travel directly to collecting electrode and hence an electric current called photoelectric current starts flowing in the circuit, which is directly proportional to the number of photoelectrons emitted by emitting electrode C.

While demonstrating the existence of electromagnetic waves, Hertz found that high voltage sparks passed across the metal electrodes of the detector loop more easily when the cathode was illuminated by ultraviolet light from an arc lamp. The ultraviolet light falling on the metal surface caused the emission of negatively charged particles, which are now known to be electrons, into the surrounding space and hence enhanced the high voltage sparks.

  1. Cathode rays were discovered by:
  1. Maxwell Clerk James.
  2. Heinrich Hertz.
  3. William Crookes.
  4. J. J. Thomson.
  1. Cathode rays consists of:
  1. Photons
  2. Electrons
  3. Pistons

  4. $\alpha$-particles

  1. Who discovered the charge on an electron for the frist time?
  1. Millikan
  2. Thomson
  3. Kelvin
  4. Coulomb
  1. The dual nature oflight is exhibited by:
  1. Diffraction and photoelectric effect.
  2. Photoelectric effect.
  3. Refraction and interference.
  4. Diffraction and reflection.
  1. ln the phenomenon of electric discharge through gases at low pressure, the coloured glow in the tube appears as a result of:
  1. Collisions between the charged particles emitted from the cathode and the atoms of the gas.
  2. Collision between different electrons of the atoms of the gas.
  3. Excitation of electrons in the atoms.
  4. Collision between the atoms of the gas.
→
The electrostatic force on a small sphere of charge $0.4 \mu C$ due to another small sphere of charge $-0.8 \mu C$ in air is 0.2 N (a) What is the distance between the two spheres? (b) What is the force on the second sphere due to the first?
→
The number of free electrons in a unit volume copper conductor estimated in Example 8.1 is 8.5 x 1028 per m3.How long does an electron take to drift from one end of a wire 3.0 m long to its other end? The area of cross-section of the wire is 2.0 x 10-6 m2and it is carrying a current of 3.0 A.
→
Find the acceleration due to gravity of the moon at a point 1000km above the moon's surface. The mass of the moon is 7.4 × 1022kg and its radius is 1740km.
→
Suppose the bent part of the frame of the previous problem has a thermal conductivity of 780Js-1m-1°C-1 whereas it is 390Js-1m-1°C-1 for the straight part. Calculate the ratio of the rate of heat flow through the bent part to the rate of heat flow through the straight part.
→
A collision experiment is done on a horizontal table kept in an elevator. Do you expect a change in the results if the elevator is accelerated up or down because of the noninertial character of the frame?
→
What do you mean by coherent sources of light? How are these obtained in the laboratory ?
→
There are materials which absorb photons of shorter wavelength and emit photons of longer wavelength. Can there be stable substances which absorb photons of larger wavelength and emit light of shorter wavelength.
→