181 + Interview Questions in ELECTRON IN GENERAL AWARENESS Page 4 InterviewSolution

151.	When photons of energy `4.25 eV` strike the surface of metal A, the ejected photoelectrons have maximum kinetic energy `T_(A)` eV and De-broglie wavelength `lambda_(A)`. The maximum energy of photoelectron liberated from another metal B by photon of energy 4.70 eV is `T_(B) = (T_(A) - 1.50) eV` if the de Brogle wavelength of these photoelectrons is `lambda_(B) = 2 lambda_(A) `, thenA. The work function of A is 2.25 eVB. The work function of B is 4.20 eVC. `T_(A) = 2.00 eV`D. `T_(B) = 2.75 eV`
Answer» Correct Answer - A::B::C

Discussion

152.	When radiation of wavelength `lambda ` is incident on a metallic surface , the stopping potential is `4.8 "volts"` . If the same surface is illuminated with radiation of double the wavelength , then the stopping potential becomes `1.6 "volts"`. Then the threshold wavelength for the surface isA. `2 lamda`B. `4 lamda`C. `6 lamda`D. `8 lamda`
Answer» Correct Answer - B

Discussion

153.	When radiation is incident on a photoelectron emitter , the stopping potential is found to be `9 volts` . If `e//m` for the electrons is `1.8 xx 10^(11) C kg^(-1)` the maximum velocity of the ejected electrons isA. `6 xx 10^(5) ms^(-1)`B. `8 xx 10^(5) ms^(-1)`C. `1.8 xx 10^(6) ms^(-1)`D. `1.8 xx 10^(5) ms^(-1)`
Answer» Correct Answer - C

Discussion

154.	The photoelectric threshold wavelength for potassium (work function being `2 eV`) isA. 310 nmB. 620 nmC. 1200 nmD. 2100 nm
Answer» Correct Answer - B

Discussion

155.	The lowest frequency of light that will cause the emission of photoelectrons from the surface of a metal ( for which work function is `1.65 eV`) will beA. `4xx10^(10) Hz`B. `4 xx 10^(11) Hz`C. `4 xx 10^(14) Hz`D. `4 xx 10^(-10) Hz`
Answer» Correct Answer - C

Discussion

156.	The stopping potential as a function of the frequency of the incident radiation is plotted for two different photoelectric surfaces `A` and `B` . The graphs show that work function of `A` is A. Greater than that of BB. Smaller than that of BC. Equal to that of BD. No inference can be drawn about their work functions from the given graphs
Answer» Correct Answer - C

Discussion

157.	If the work function of a photo - metal is `6.825 eV`. Its threshold wavelength will be `( c = 3 xx 10^(8) m//s)`A. 1200 ÅB. 1800 ÅC. 2400 ÅD. 3600 Å
Answer» Correct Answer - B

Discussion

158.	A photon energy `3.4 eV` is incident on a metal having work function `2 eV`. The maximum `K.E.` of photoelectrons is equal toA. 1.4 eVB. 1.7 eVC. 5.4 eVD. 6.8 eV
Answer» Correct Answer - A

Discussion

159.	Which of the following is dependent on the intensity of incident radiation in a photoelectric experimentA. Work function of the surfaceB. Amount of photoelectric currenC. Stopping potential will be reducedD. Maximum kinetic energy of photoelectrons
Answer» Correct Answer - B

Discussion

160.	Light of wavelength `1824 Å`, incident on the surface of a metal , produces photo - electrons with maximum energy `5.3 eV`. When light of wavelength `1216 Å` is used , maximum energy of photoelectrons is `8.7 eV`. The work function of the metal surface isA. 3.5 eVB. 13.6 eVC. 6.8 eVD. 1.5 eV
Answer» Correct Answer - D

Discussion

161.	The work function of a metallic surface is `5.01 eV`. The photo - electrons are emitted when light of wavelength `2000 Å` falls on it . The potential difference applied to stop the fastest photo - electrons is `[ h = 4.14 xx 10^(-15) eV sec]`A. 1.2 voltsB. 2.24 voltsC. 3.6 voltsD. 4.8 volts
Answer» Correct Answer - A

Discussion

162.	An electron beam in an X-ray tube is acclerated through a potential difference of 50000 volts. These are then made to fall on a tungsten target The shortest wavelength of the X-ray emitted by the tube isA. 2.0 ÅB. 0.25 mmC. 0.25 cmD. 0.025 nm
Answer» Correct Answer - D

Discussion

163.	The figure represents the observed intensity of `X` - rays emitted by an `X` - ray tube as a function of wavelength . The sharp peaks `A` and `B` denote A. Band spectrumB. Continuous spectrumC. Characteristic radiationsD. White radiations
Answer» Correct Answer - C

Discussion

164.	Light of wavelength `5000 Å` falls on a sensitive plate with photoelectric work function of `1.9 eV`. The kinetic energy of the photoelectron emitted will beA. 0.58 eVB. 2.48 eVC. 1.24 eVD. 1.16 eV
Answer» Correct Answer - A

Discussion

165.	The minimum wavelength of photon is `5000 Å` , its energy will beA. 2.5 eVB. 50 eVC. 5.48 eVD. 7.48 eV
Answer» Correct Answer - A

Discussion

166.	The momentum of the photon of wavelength `5000 Å` will beA. `1.3 xx 10^(-27) kg-m//sec`B. `1.3 xx 10^(-28) kg-m//sec`C. `4 xx 10^(29) kg-m//sec`D. `4 xx 10^(-18) kg-m//sec`
Answer» Correct Answer - A

Discussion

167.	If `lambda_(1)` and `lambda_(2)` are the wavelength of characteristic `X` - rays and gamma rays respectively , then the relation between them isA. `lamda_(1) = (1)/(lamda_(2))`B. `lamda_(1) = lamda_(2)`C. `lamda_(1) gt lamda_(2)`D. `lamda_(1) lt lamda_(2)`
Answer» Correct Answer - C

Discussion

168.	If the potential difference between the anode and cathode of the X-ray tube is increases A. The peaks at R and S would move to shorter wavelengthB. The peaks at R and S would remain at the same wavelengthC. The cut off wavelength at P would decreaseD. (b) and (c) both are correct
Answer» Correct Answer - D

Discussion

169.	Find the cutoff wavelength for the continuous X-rays coming from an X-ray tube operating at `40 kV`.A. 0.31 ÅB. 3.1 ÅC. 31 ÅD. 311 Å
Answer» Correct Answer - A

Discussion

170.	If the cathode-anode potential difference in an X-ray tube be 10 V then the maximum energy of X-ray photon can beA. 10 JB. 10 MeVC. 10 MeVD. 10 KeV
Answer» Correct Answer - C

Discussion

171.	The maximum kinetic energy of the electrons hitting a target so as to produce X-ray of wavelength 1 Å isA. 13375 eVB. 12375 eVC. 14375 eVD. 15375 eV
Answer» Correct Answer - B

Discussion

172.	The potential difference applied to an X-ray tube is 5k V and the current through it is 3.2 mA. Then, the number of electrons striking the target per second is. (a) `2xx10^16` (b) `5xx10^6` (c ) `1xx10^17` (d) `4xx10^15`.A. `2 xx 10^(16)`B. `5 xx 10^(16)`C. `1xx10^(17)`D. `4xx10^(15)`
Answer» Correct Answer - A

Discussion

173.	If the potential difference applied across x-ray tube is V volts, then approximately minimum wavelength of the emitted X-rays will beA. `(1227)/(sqrt(V)) Å`B. `(1240)/(V) Å`C. `(2400)/(V) Å`D. `(12400)/(V) Å`
Answer» Correct Answer - D

Discussion

174.	The energy of a photon of light with wavelength `5000 Å` is approximately `2.5 eV`. This way the energy of an X - ray photon with wavelength `1 Å` would beA. 2.5/5000 eVB. `2.5//(5000)^(2)eV`C. `2.5 xx 5000 eV`D. `2.5 xx (5000)^(2) eV`
Answer» Correct Answer - C

Discussion

175.	When cathode rays (tube voltage - 10 kV) collide with the anode of high atomic weight then we getA. Positive raysB. X-raysC. Gamma raysD. Canal rays
Answer» Correct Answer - B

Discussion

176.	An `X` - ray tube with a copper target emits `Cu K_(alpha)` line of wavelength `1.50 Å`. What should be the minimum voltage through which electrons are to be accelarated to produce this wavelength of `X` - rays ? `( h = 6.63 xx 10^(-34) J - sec , c = 3 xx 10^(8) m//s)`A. 8280 VB. 828 VC. 82800 VD. 8.28 V
Answer» Correct Answer - A

Discussion

177.	The minimum wavelength of X-ray emitted by X-rays tube is 0.4125 Å. The accelerating voltage isA. 30 kVB. 50 kVC. 80 kVD. 60 kV
Answer» Correct Answer - A

Discussion

178.	The wavelength `lambda` of the `K_(a)` line of characteristic `X` - ray spectra varies with atomic number approximatelyA. `lamda prop Z`B. `lamda prop sqrt(Z)`C. `lamda prop (1)/(Z^(2))`D. `lamda prop (1)/(sqrt(Z))`
Answer» Correct Answer - C

Discussion

179.	The wavelength of `k_(alpha) ` X- rays produced by an X - rays tube is `0.76 Å` . The atomic number of the anode material of the tube is …….A. 20B. 60C. 40D. 80
Answer» Correct Answer - C

Discussion

180.	The wavelength of `K_(alpha)` line for an element of atomic number `43 is lambda`. Then the wavelength of `K_(alpha)` line for an element of atomic number `29` isA. `(43)/(29) lamda`B. `(42)/(28) lamda`C. `(9)/(4) lamda`D. `(4)/(9) lamda`
Answer» Correct Answer - C

Discussion

181.	The `K_(alpha)` `X` - rays arising from a cobalt `(z = 27)` target have a wavelength of `179 pm`. The `K_(alpha)` `X` - rays arising from a nickel target `(z = 28)` isA. `gt 179` pmB. `lt 179` pmC. `=179` pmD. None of these
Answer» Correct Answer - B

Discussion

Explore topic-wise InterviewSolutions in .

The photoelectric threshold wavelength for potassium (work function being `2 eV`) isA. 310 nmB. 620 nmC. 1200 nmD. 2100 nm

The lowest frequency of light that will cause the emission of photoelectrons from the surface of a metal ( for which work function is `1.65 eV`) will beA. `4xx10^(10) Hz`B. `4 xx 10^(11) Hz`C. `4 xx 10^(14) Hz`D. `4 xx 10^(-10) Hz`

If the work function of a photo - metal is `6.825 eV`. Its threshold wavelength will be `( c = 3 xx 10^(8) m//s)`A. 1200 ÅB. 1800 ÅC. 2400 ÅD. 3600 Å

A photon energy `3.4 eV` is incident on a metal having work function `2 eV`. The maximum `K.E.` of photoelectrons is equal toA. 1.4 eVB. 1.7 eVC. 5.4 eVD. 6.8 eV

Which of the following is dependent on the intensity of incident radiation in a photoelectric experimentA. Work function of the surfaceB. Amount of photoelectric currenC. Stopping potential will be reducedD. Maximum kinetic energy of photoelectrons

Light of wavelength `1824 Å`, incident on the surface of a metal , produces photo - electrons with maximum energy `5.3 eV`. When light of wavelength `1216 Å` is used , maximum energy of photoelectrons is `8.7 eV`. The work function of the metal surface isA. 3.5 eVB. 13.6 eVC. 6.8 eVD. 1.5 eV

The work function of a metallic surface is `5.01 eV`. The photo - electrons are emitted when light of wavelength `2000 Å` falls on it . The potential difference applied to stop the fastest photo - electrons is `[ h = 4.14 xx 10^(-15) eV sec]`A. 1.2 voltsB. 2.24 voltsC. 3.6 voltsD. 4.8 volts

An electron beam in an X-ray tube is acclerated through a potential difference of 50000 volts. These are then made to fall on a tungsten target The shortest wavelength of the X-ray emitted by the tube isA. 2.0 ÅB. 0.25 mmC. 0.25 cmD. 0.025 nm

The figure represents the observed intensity of `X` - rays emitted by an `X` - ray tube as a function of wavelength . The sharp peaks `A` and `B` denote A. Band spectrumB. Continuous spectrumC. Characteristic radiationsD. White radiations

Light of wavelength `5000 Å` falls on a sensitive plate with photoelectric work function of `1.9 eV`. The kinetic energy of the photoelectron emitted will beA. 0.58 eVB. 2.48 eVC. 1.24 eVD. 1.16 eV

The minimum wavelength of photon is `5000 Å` , its energy will beA. 2.5 eVB. 50 eVC. 5.48 eVD. 7.48 eV

The momentum of the photon of wavelength `5000 Å` will beA. `1.3 xx 10^(-27) kg-m//sec`B. `1.3 xx 10^(-28) kg-m//sec`C. `4 xx 10^(29) kg-m//sec`D. `4 xx 10^(-18) kg-m//sec`

If `lambda_(1)` and `lambda_(2)` are the wavelength of characteristic `X` - rays and gamma rays respectively , then the relation between them isA. `lamda_(1) = (1)/(lamda_(2))`B. `lamda_(1) = lamda_(2)`C. `lamda_(1) gt lamda_(2)`D. `lamda_(1) lt lamda_(2)`

If the potential difference between the anode and cathode of the X-ray tube is increases A. The peaks at R and S would move to shorter wavelengthB. The peaks at R and S would remain at the same wavelengthC. The cut off wavelength at P would decreaseD. (b) and (c) both are correct

Find the cutoff wavelength for the continuous X-rays coming from an X-ray tube operating at `40 kV`.A. 0.31 ÅB. 3.1 ÅC. 31 ÅD. 311 Å

If the cathode-anode potential difference in an X-ray tube be 10 V then the maximum energy of X-ray photon can beA. 10 JB. 10 MeVC. 10 MeVD. 10 KeV

The maximum kinetic energy of the electrons hitting a target so as to produce X-ray of wavelength 1 Å isA. 13375 eVB. 12375 eVC. 14375 eVD. 15375 eV

The potential difference applied to an X-ray tube is 5k V and the current through it is 3.2 mA. Then, the number of electrons striking the target per second is. (a) `2xx10^16` (b) `5xx10^6` (c ) `1xx10^17` (d) `4xx10^15`.A. `2 xx 10^(16)`B. `5 xx 10^(16)`C. `1xx10^(17)`D. `4xx10^(15)`

If the potential difference applied across x-ray tube is V volts, then approximately minimum wavelength of the emitted X-rays will beA. `(1227)/(sqrt(V)) Å`B. `(1240)/(V) Å`C. `(2400)/(V) Å`D. `(12400)/(V) Å`

The energy of a photon of light with wavelength `5000 Å` is approximately `2.5 eV`. This way the energy of an X - ray photon with wavelength `1 Å` would beA. 2.5/5000 eVB. `2.5//(5000)^(2)eV`C. `2.5 xx 5000 eV`D. `2.5 xx (5000)^(2) eV`

When cathode rays (tube voltage - 10 kV) collide with the anode of high atomic weight then we getA. Positive raysB. X-raysC. Gamma raysD. Canal rays

The minimum wavelength of X-ray emitted by X-rays tube is 0.4125 Å. The accelerating voltage isA. 30 kVB. 50 kVC. 80 kVD. 60 kV

The wavelength `lambda` of the `K_(a)` line of characteristic `X` - ray spectra varies with atomic number approximatelyA. `lamda prop Z`B. `lamda prop sqrt(Z)`C. `lamda prop (1)/(Z^(2))`D. `lamda prop (1)/(sqrt(Z))`

The wavelength of `k_(alpha) ` X- rays produced by an X - rays tube is `0.76 Å` . The atomic number of the anode material of the tube is …….A. 20B. 60C. 40D. 80

The wavelength of `K_(alpha)` line for an element of atomic number `43 is lambda`. Then the wavelength of `K_(alpha)` line for an element of atomic number `29` isA. `(43)/(29) lamda`B. `(42)/(28) lamda`C. `(9)/(4) lamda`D. `(4)/(9) lamda`

The `K_(alpha)` `X` - rays arising from a cobalt `(z = 27)` target have a wavelength of `179 pm`. The `K_(alpha)` `X` - rays arising from a nickel target `(z = 28)` isA. `gt 179` pmB. `lt 179` pmC. `=179` pmD. None of these