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MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 11851. |
X-rays region lies between [CPMT 1990] |
| A. | Short radiowave and visible region |
| B. | Visible and ultraviolet region |
| C. | Gamma rays and ultraviolet region |
| D. | Short radiowave and long radiowave |
| Answer» D. Short radiowave and long radiowave | |
| 11852. |
When the accelerating voltage applied on the electrons increased beyond a critical value [CPMT 1975] |
| A. | Only the intensity of the various wavelengths is increased |
| B. | Only the wavelength of characteristic relation is affected |
| C. | The spectrum of white radiation is unaffected |
| D. | The intensities of characteristic lines relative to the white spectrum are increased but there is no change in their wavelength |
| Answer» E. | |
| 11853. |
The penetrating power of X-rays increases with the [MP PMT 1984] |
| A. | Increase in its velocity |
| B. | Increase in its frequency |
| C. | Increase in its intensity |
| D. | Decrease in its velocity |
| Answer» C. Increase in its intensity | |
| 11854. |
The minimum wavelength of X-rays produced by electrons accelerated by a potential difference of volts is equal to [CPMT 1986, 88, 91; RPMT 1997; RPMT 1997, 98; MP PET 1997, 98; MP PMT 1996, 98, 2003; UPSEAT 2005] |
| A. | \[\frac{eV}{hc}\] |
| B. | \[\frac{eh}{cV}\] |
| C. | \[\frac{hc}{eV}\] |
| D. | \[\frac{cV}{eh}\] |
| Answer» D. \[\frac{cV}{eh}\] | |
| 11855. |
The wavelength of most energetic X-rays emitted when a metal target is bombarded by 40KeV electrons, is approximately (\[h=6.62\times {{10}^{-34}}\] J-sec; 1 eV = \[1.6\times {{10}^{-19}}\]J; c = \[3\times {{10}^{8}}\,m/s)\] [MNR 1991; MP PMT 1999; UPSEAT 2000; Pb. PET 2004] |
| A. | 300 Å |
| B. | 10 Å |
| C. | 4 Å |
| D. | 0.31 Å |
| Answer» E. | |
| 11856. |
In producing X-rays a beam of electrons accelerated by a potential difference V is made to strike a metal target. For what value of V, X-rays will have the lowest wavelength of 0.3094 Å [CPMT 1982; NCERT 1986, 87] |
| A. | 10 kV |
| B. | 20 kV |
| C. | 30 kV |
| D. | 40 Kv |
| Answer» E. | |
| 11857. |
The wavelength of the most energetic X?ray emitted when a metal target is bombarded by 100 KeV electrons is approximately [MP PET 1996] |
| A. | 12 Å |
| B. | 4 |
| C. | 0.31 Å |
| D. | 0.124 Å |
| Answer» E. | |
| 11858. |
What determines the hardness of the X-rays obtained from the Coolige tube [RPMT 1996] |
| A. | Current in the filament |
| B. | Pressure of air in the tube |
| C. | Nature of target |
| D. | Potential difference between cathode and target |
| Answer» E. | |
| 11859. |
The approximate wavelength of a photon of energy 2.48 eV is |
| A. | 500 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] |
| B. | 5000 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] |
| C. | 2000 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] |
| D. | 1000 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] |
| Answer» C. 2000 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] | |
| 11860. |
Wavelength of a 1 keV photon is \[1.24\times {{10}^{-9}}m\]. What is the frequency of 1 MeV photon |
| A. | \[1.24\times {{10}^{15}}Hz\] |
| B. | \[2.4\times {{10}^{20}}Hz\] |
| C. | \[1.24\times {{10}^{18}}Hz\] |
| D. | \[2.4\times {{10}^{23}}Hz\] |
| Answer» C. \[1.24\times {{10}^{18}}Hz\] | |
| 11861. |
The momentum of a photon is \[2\times {{10}^{-16}}\]gm-cm/sec. Its energy is |
| A. | \[0.61\times {{10}^{-26}}erg\] |
| B. | \[2.0\times {{10}^{-26}}erg\] |
| C. | \[6\times {{10}^{-6}}erg\] |
| D. | \[6\times {{10}^{-8}}erg\] |
| Answer» D. \[6\times {{10}^{-8}}erg\] | |
| 11862. |
The kinetic energy of an electron with de-Broglie wavelength of 0.3 nanometer is |
| A. | 0.168 eV |
| B. | 16.8 eV |
| C. | 1.68 eV |
| D. | 2.5 eV |
| Answer» C. 1.68 eV | |
| 11863. |
The kinetic energy of electron and proton is \[{{10}^{-32}}J\]. Then the relation between their de-Broglie wavelengths is |
| A. | \[{{\lambda }_{p}}<{{\lambda }_{e}}\] |
| B. | \[{{\lambda }_{p}}>{{\lambda }_{e}}\] |
| C. | \[{{\lambda }_{p}}={{\lambda }_{e}}\] |
| D. | \[{{\lambda }_{p}}=2{{\lambda }_{e}}\] |
| Answer» B. \[{{\lambda }_{p}}>{{\lambda }_{e}}\] | |
| 11864. |
The de-Broglie wavelength of an electron having \[80eV\] of energy is nearly (\[1\,eV=\text{ }1.6\times {{10}^{19}}J,\] Mass of electron \[=9\times {{10}^{-31}}kg\] Planks constant \[=6.6\times {{10}^{-34}}J\text{-}\,\sec \]) |
| A. | 140 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] |
| B. | 0.14 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] |
| C. | 14 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] |
| D. | 1.4 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] |
| Answer» C. 14 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] | |
| 11865. |
There are \[{{n}_{1}}\] photons of frequency \[{{\gamma }_{1}}\] in a beam of light. In an equally energetic beam, there are \[{{n}_{2}}\] photons of frequency \[{{\gamma }_{2}}\]. Then the correct relation is |
| A. | \[\frac{{{n}_{1}}}{{{n}_{2}}}=1\] |
| B. | \[\frac{{{n}_{1}}}{{{n}_{2}}}=\frac{{{\gamma }_{1}}}{{{\gamma }_{2}}}\] |
| C. | \[\frac{{{n}_{1}}}{{{n}_{2}}}=\frac{{{\gamma }_{2}}}{{{\gamma }_{1}}}\] |
| D. | \[\frac{{{n}_{1}}}{{{n}_{2}}}=\frac{\gamma _{1}^{2}}{\gamma _{2}^{2}}\] |
| Answer» D. \[\frac{{{n}_{1}}}{{{n}_{2}}}=\frac{\gamma _{1}^{2}}{\gamma _{2}^{2}}\] | |
| 11866. |
The energy of a photon of light with wavelength 5000 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] is approximately 2.5 eV. This way the energy of an X-ray photon with wavelength 1\[\overset{\text{o}}{\mathop{\text{A}}}\,\] would be |
| A. | 2.5/5000 eV |
| B. | \[2.5/{{(5000)}^{2}}eV\] |
| C. | \[2.5\times 5000\ eV\] |
| D. | \[2.5\times {{(5000)}^{2}}eV\] |
| Answer» D. \[2.5\times {{(5000)}^{2}}eV\] | |
| 11867. |
A photon in motion has a mass |
| A. | \[c/h\nu \] |
| B. | \[h/\nu \] |
| C. | \[h\nu \] |
| D. | \[h\nu /{{c}^{2}}\] |
| Answer» E. | |
| 11868. |
A photon, an electron and a uranium nucleus all have the same wavelength. The one with the most energy |
| A. | Is the photon |
| B. | Is the electron |
| C. | Is the uranium nucleus |
| D. | Depends upon the wavelength and the properties of the particle. |
| Answer» B. Is the electron | |
| 11869. |
In photoelectric effect, the K.E. of electrons emitted from the metal surface depends upon |
| A. | Intensity of light |
| B. | Frequency of incident light |
| C. | Velocity of incident light |
| D. | Both intensity and velocity of light |
| Answer» C. Velocity of incident light | |
| 11870. |
A photon of energy 8 eV is incident on metal surface of threshold frequency \[1.6\times {{10}^{15}}Hz.\] The maximum kinetic energy of the photoelectrons emitted (in eV) (Take \[h=6\times {{10}^{-34}}Js)\]. |
| A. | 1.6 |
| B. | 6 |
| C. | 2 |
| D. | 1.2 |
| Answer» B. 6 | |
| 11871. |
Light of wavelength 4000 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] is incident on a sodium surface for which the threshold wave length of photo electrons is 5420 \[\overset{\text{o}}{\mathop{\text{A}}}\,\]. The work function of sodium is |
| A. | 4.58 eV |
| B. | 2.29 eV |
| C. | 1.14 eV |
| D. | 0.57 eV |
| Answer» C. 1.14 eV | |
| 11872. |
Ultraviolet radiations of \[6.2\,eV\] falls on an aluminium surface (work function \[4.2\ eV\]). The kinetic energy in joules of the fastest electron emitted is approximately |
| A. | \[3.2\times {{10}^{-21}}\] |
| B. | \[3.2\times {{10}^{-19}}\] |
| C. | \[3.2\times {{10}^{-17}}\] |
| D. | \[3.2\times {{10}^{-15}}\] |
| Answer» C. \[3.2\times {{10}^{-17}}\] | |
| 11873. |
The electrons are emitted in the photoelectric effect from a metal surface |
| A. | Only if the frequency of the incident radiation is above a certain threshold value |
| B. | Only if the temperature of the surface is high |
| C. | At a rate that is independent of the nature of the metal |
| D. | With a maximum velocity proportional to the frequency of the incident radiation |
| Answer» B. Only if the temperature of the surface is high | |
| 11874. |
A light of wavelength \[\lambda \] and intensity l is incident normally on the surface. If reflection coefficient of surface is r, the pressure exerted by light on the surface is equal to |
| A. | \[\frac{2I}{c}\] |
| B. | \[\frac{I}{c}r\] |
| C. | \[\frac{I}{c}\left( I+r \right)\] |
| D. | \[\frac{I}{c}\left( I-r \right)\] |
| Answer» D. \[\frac{I}{c}\left( I-r \right)\] | |
| 11875. |
Photons with energy 5 eV are incident on a cathode C, on a photoelectric cell. The maximum energy of the emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A if the stopping potential of A relative to C is |
| A. | 3V |
| B. | -3V |
| C. | -1V |
| D. | 4V |
| Answer» C. -1V | |
| 11876. |
An X-ray tube with Cu target is operated at 25 kV. The glancing angle for a \[NaCl.\] Crystal for the \[Cu\]\[{{K}_{\alpha }}\] line is \[15.8{}^\circ \]. Find the wavelength of this line. (\[NaCl=2.82\overset{\text{o}}{\mathop{\text{A}}}\,\] for, \[\text{h=6}\text{.62 }\!\!\times\!\!\text{ 1}{{\text{0}}^{-\,27}}\text{erg-sec}\]) |
| A. | 3.06 A |
| B. | 1.53 A |
| C. | 0.75 A |
| D. | None of these |
| Answer» C. 0.75 A | |
| 11877. |
A particle having mass \[1.67\times {{10}^{-27}}\] kg moving at a speed v absorbs a photon of wavelength 122 nm and stops. The value of v is |
| A. | \[3.25m{{s}^{-1}}\] |
| B. | \[1.28m{{s}^{-1}}\] |
| C. | \[0.82\text{ }m{{s}^{-1}}\] |
| D. | \[0.33m{{s}^{-1}}\] |
| Answer» B. \[1.28m{{s}^{-1}}\] | |
| 11878. |
X-rays are produced in an X-ray tube operating at a given accelerating voltage. The wavelength of the continuous X-rays has values from |
| A. | \[0\text{ to }\infty \] |
| B. | \[{{\lambda }_{\min }}\text{ to }\infty \text{ where }{{\lambda }_{\max }}M\infty \] |
| C. | \[0\text{ to }{{\lambda }_{\max }}\text{ where }{{\lambda }_{\max }}<\infty \] |
| D. | \[{{\lambda }_{\min }}\text{ to }{{\lambda }_{\max }}\text{ where 0}{{\lambda }_{\min }}<{{\lambda }_{\max }}<\infty \] |
| Answer» C. \[0\text{ to }{{\lambda }_{\max }}\text{ where }{{\lambda }_{\max }}<\infty \] | |
| 11879. |
An ultraviolet light bulb, emitting 400 nm and an infrared light bulb, emitting at 700nm, each are rated at 130 W. Then the ratio of the number of photons emitted per second by the UV and IR sources is - |
| A. | 0.57 |
| B. | 1.75 |
| C. | 28 |
| D. | 0.04 |
| Answer» B. 1.75 | |
| 11880. |
The potential energy of a particle of mass m is given by \[V\left( x \right)=\left\{ \begin{matrix} {{E}_{0}}; & 0\le x\le 1 \\ 0; & x>1 \\ \end{matrix} \right\}\]\[{{\lambda }_{1}}\] and \[{{\lambda }_{2}}\]are the de-Broglie wavelengths of the particle, when \[0\le x\le 1\] and \[x>1\]respectively. If the total energy of particle is\[2{{E}_{0}}\], find \[{{\lambda }_{1}}/{{\lambda }_{2}}\]. |
| A. | \[\sqrt{2}\] |
| B. | \[\sqrt{3}\] |
| C. | \[\sqrt{5}\] |
| D. | \[2\sqrt{2}\] |
| Answer» B. \[\sqrt{3}\] | |
| 11881. |
The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (Kelvin) and mass m, is:- |
| A. | \[\frac{h}{\sqrt{3\,mk\,T}}\] |
| B. | \[\frac{2\,h}{\sqrt{3\,mk\,T}}\] |
| C. | \[\frac{2\,h}{\sqrt{mk\,T}}\] |
| D. | \[\frac{h}{\sqrt{mk\,T}}\] |
| Answer» B. \[\frac{2\,h}{\sqrt{3\,mk\,T}}\] | |
| 11882. |
An electron is accelerated through a potential difference of V volt. It has a wavelength associated with them is. |
| A. | V volt |
| B. | 1837V volt |
| C. | V/1837volt |
| D. | \[\sqrt{1837}\]V volt |
| Answer» D. \[\sqrt{1837}\]V volt | |
| 11883. |
In photoelectric effect if the intensity of light is doubled then maximum kinetic energy of photoelectrons will become [RPMT 1999] |
| A. | Double |
| B. | Half |
| C. | Four time |
| D. | No change |
| Answer» E. | |
| 11884. |
The photoelectric threshold wavelength of a certain metal is 3000Å. If the radiation of 2000Å is incident on the metal [MNR 1998; KCET 1994] |
| A. | Electrons will be emitted |
| B. | Positrons will be emitted |
| C. | Protons will be emitted |
| D. | Electrons will not be emitted |
| Answer» B. Positrons will be emitted | |
| 11885. |
An AIR station is broadcasting the waves of wavelength 300 metres. If the radiating power of the transmitter is 10 kW, then the number of photons radiated per second is [MP PET 1989; RPMT 2000] |
| A. | \[1.5\times {{10}^{29}}\] |
| B. | \[1.5\times {{10}^{31}}\] |
| C. | \[1.5\times {{10}^{33}}\] |
| D. | \[1.5\times {{10}^{35}}\] |
| Answer» C. \[1.5\times {{10}^{33}}\] | |
| 11886. |
The frequency of the incident light falling on a photosensitive metal plate is doubled, the kinetic energy of the emitted photoelectrons is [Roorkee 1992] |
| A. | Double the earlier value |
| B. | Unchanged |
| C. | More than doubled |
| D. | Less than doubled |
| Answer» D. Less than doubled | |
| 11887. |
The work function of a photoelectric material is 3.3 eV. The threshold frequency will be equal to [UPSEAT 1999] |
| A. | \[8\times {{10}^{4}}Hz\] |
| B. | \[8\times {{10}^{56}}Hz\] |
| C. | \[8\times {{10}^{10}}Hz\] |
| D. | \[8\times {{10}^{14}}Hz\] |
| Answer» E. | |
| 11888. |
Energy conversion in a photoelectric cell takes place from [AFMC 1993; MP PET 1996; MP PMT 1996] |
| A. | Chemical to electrical |
| B. | Magnetic to electrical |
| C. | Optical to electrical |
| D. | Mechanical to electrical |
| Answer» D. Mechanical to electrical | |
| 11889. |
Photo cell is a device to [MP PET 1993] |
| A. | Store photons |
| B. | Measure light intensity |
| C. | Convert photon energy into mechanical energy |
| D. | Store electrical energy for replacing storage batteries |
| Answer» C. Convert photon energy into mechanical energy | |
| 11890. |
A radio transmitter operates at a frequency of 880 kHz and a power of 10 kW. The number of photons emitted per second are [CBSE PMT 1990; MP PET 1990] |
| A. | \[1.72\times {{10}^{31}}\] |
| B. | \[1327\times {{10}^{34}}\] |
| C. | \[13.27\times {{10}^{34}}\] |
| D. | \[0.075\times {{10}^{-34}}\] |
| Answer» B. \[1327\times {{10}^{34}}\] | |
| 11891. |
A photon of energy 3.4 eV is incident on a metal having work function 2 eV. The maximum K.E. of photo-electrons is equal to [MP PET 1991] |
| A. | 1.4 eV |
| B. | 1.7 eV |
| C. | 5.4 eV |
| D. | 6.8 eV |
| Answer» B. 1.7 eV | |
| 11892. |
In a dark room of photography, generally red light is used. The reason is |
| A. | Most of the photographic films are not sensitive to red light |
| B. | The frequency for red light is low and hence the energy \[hv\]of photons is less |
| C. | (a) and (b) both |
| D. | None of the above |
| Answer» D. None of the above | |
| 11893. |
A metal surface of work function 1.07 eV is irradiated with light of wavelength 332 nm. The retarding potential required to stop the escape of photo-electrons is [MP PMT 1992] |
| A. | 4.81 eV |
| B. | 3.74 eV |
| C. | 2.66 eV |
| D. | 1.07 eV |
| Answer» D. 1.07 eV | |
| 11894. |
Which of the following is true for photon [RPET 2001] |
| A. | \[E=\frac{hc}{\lambda }\] |
| B. | \[E=\frac{1}{2}m{{u}^{2}}\] |
| C. | \[p=\frac{E}{2v}\] |
| D. | \[E=\frac{1}{2}m{{c}^{2}}\] |
| Answer» B. \[E=\frac{1}{2}m{{u}^{2}}\] | |
| 11895. |
Frequency of photon having energy 66 eV is [CPMT PMT 1997] |
| A. | \[8\times {{10}^{-15}}Hz\] |
| B. | \[12\times {{10}^{-15}}Hz\] |
| C. | \[16\times {{10}^{15}}Hz\] |
| D. | None of these |
| Answer» D. None of these | |
| 11896. |
Wavelength of a 1 keV photon is \[1.24\times {{10}^{-9}}m\]. What is the frequency of 1 MeV photon [CBSE PMT 1993; MP PET 2005] |
| A. | \[1.24\times {{10}^{15}}Hz\] |
| B. | \[2.4\times {{10}^{20}}Hz\] |
| C. | \[1.24\times {{10}^{18}}Hz\] |
| D. | \[2.4\times {{10}^{23}}Hz\] |
| Answer» C. \[1.24\times {{10}^{18}}Hz\] | |
| 11897. |
For photoelectric emission, tungsten requires light of 2300 Å. If light of 1800 Å wavelength is incident then emission [AFMC 2005] |
| A. | Takes place |
| B. | Don?t take place |
| C. | May or may not take place |
| D. | Depends on frequency |
| Answer» B. Don?t take place | |
| 11898. |
A photosensitive metallic surface has work function \[h{{v}_{0}}\]. If photons of energy \[2h{{v}_{0}}\] fall on this surface the electrons come out with a maximum velocity of \[4\times {{10}^{6}}\,m/s\]. When the photon energy is increases to \[5h{{v}_{0}}\] then maximum velocity of photo electron will be [CBSE PMT 2005] |
| A. | \[2\times {{10}^{6}}\,m/s\] |
| B. | \[2\times {{10}^{7}}\,m/s\] |
| C. | \[8\times {{10}^{5}}\,m/s\] |
| D. | \[8\times {{10}^{6}}\,m/s\] |
| Answer» E. | |
| 11899. |
If the threshold wavelength for sodium is 5420 Å, then the work function of sodium is [RPMT 2003] |
| A. | 4.58 eV |
| B. | 2.28 eV |
| C. | 1.14 eV |
| D. | 0.23 eV |
| Answer» C. 1.14 eV | |
| 11900. |
The velocity of photon is proportional to (where n is frequency) [Pb. PMT 2004] |
| A. | \[\frac{{{\nu }^{2}}}{2}\] |
| B. | \[\frac{1}{\sqrt{\nu }}\] |
| C. | \[\sqrt{\nu }\] |
| D. | n |
| Answer» E. | |