142236
If the photoelectric work function for a metallic surface is $4.125 \mathrm{eV}$, the cut-off wavelength for photoelectric phenomenon for the surface is
142237
An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be-
1 $\frac{24 \mathrm{hR}}{25 \mathrm{~m}}$
2 $\frac{25 \mathrm{hR}}{24 \mathrm{~m}}$
3 $\frac{24 \mathrm{~m}}{25 \mathrm{hR}}$
4 $\frac{25 \mathrm{~m}}{24 \mathrm{hR}}$
Explanation:
A Wavelength observed from transition of $n_{1}$ to $\mathrm{n}_{2}$. $\frac{1}{\lambda}=\mathrm{RZ}^{2}\left[\frac{1}{\mathrm{n}_{1}^{2}}-\frac{1}{\mathrm{n}_{2}^{2}}\right]$ $\mathrm{n}_{1}=1, \mathrm{n}_{2}=5, \mathrm{Z}=1$ $\frac{1}{\lambda}=\mathrm{R}\left[1-\frac{1}{5^{2}}\right]$ $\frac{1}{\lambda}=\frac{24}{25} \mathrm{R}$ Apply momentum conservation Momentum of photon $=$ Momentum of atom. $\frac{\mathrm{h}}{\lambda}=\mathrm{mv}$ $\mathrm{v}=\frac{\mathrm{h}}{\mathrm{m} \lambda}=\frac{\mathrm{h}}{\mathrm{m}} \times \frac{24}{25} \mathrm{R}$ $\mathrm{v}=\frac{24 \mathrm{hR}}{25 \mathrm{~m}}$
BCECE-2017
Dual nature of radiation and Matter
142238
The anode voltage of a photocell is kept fixed. The wavelength $\lambda$ of the light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows
1
2
3
4
Explanation:
D We know that, $\quad \text { Intensity }=\frac{\text { Power }}{\text { Area }}=\frac{\text { Energy }}{\text { Area } \times \text { time }}$ $\therefore \quad \text { Intensity } \propto \mathrm{E} \propto \frac{1}{\lambda} \quad\left(\because \mathrm{E}=\frac{\mathrm{hc}}{\lambda}\right)$ For photoelectric effect- $\mathrm{I}=$ photoelectric current $\mathrm{I} \propto \text { energy } \propto \frac{1}{\lambda}$ $\mathrm{I} \propto \frac{1}{\lambda}$
AIIMS-2017
Dual nature of radiation and Matter
142231
Assertion: Threshold frequency depends on material of metal used. Reason: Threshold wavelength $\propto$ Threshold frequency.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
C Threshold frequency depends on material of metal used for most metal like zinc, Cadmium, magnesium, threshold frequency lie in ultraviolet region Threshold frequency is inversely proportional to threshold wavelength. $v \propto \frac{1}{\lambda}$
NEET Test Series from KOTA - 10 Papers In MS WORD
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Dual nature of radiation and Matter
142236
If the photoelectric work function for a metallic surface is $4.125 \mathrm{eV}$, the cut-off wavelength for photoelectric phenomenon for the surface is
142237
An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be-
1 $\frac{24 \mathrm{hR}}{25 \mathrm{~m}}$
2 $\frac{25 \mathrm{hR}}{24 \mathrm{~m}}$
3 $\frac{24 \mathrm{~m}}{25 \mathrm{hR}}$
4 $\frac{25 \mathrm{~m}}{24 \mathrm{hR}}$
Explanation:
A Wavelength observed from transition of $n_{1}$ to $\mathrm{n}_{2}$. $\frac{1}{\lambda}=\mathrm{RZ}^{2}\left[\frac{1}{\mathrm{n}_{1}^{2}}-\frac{1}{\mathrm{n}_{2}^{2}}\right]$ $\mathrm{n}_{1}=1, \mathrm{n}_{2}=5, \mathrm{Z}=1$ $\frac{1}{\lambda}=\mathrm{R}\left[1-\frac{1}{5^{2}}\right]$ $\frac{1}{\lambda}=\frac{24}{25} \mathrm{R}$ Apply momentum conservation Momentum of photon $=$ Momentum of atom. $\frac{\mathrm{h}}{\lambda}=\mathrm{mv}$ $\mathrm{v}=\frac{\mathrm{h}}{\mathrm{m} \lambda}=\frac{\mathrm{h}}{\mathrm{m}} \times \frac{24}{25} \mathrm{R}$ $\mathrm{v}=\frac{24 \mathrm{hR}}{25 \mathrm{~m}}$
BCECE-2017
Dual nature of radiation and Matter
142238
The anode voltage of a photocell is kept fixed. The wavelength $\lambda$ of the light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows
1
2
3
4
Explanation:
D We know that, $\quad \text { Intensity }=\frac{\text { Power }}{\text { Area }}=\frac{\text { Energy }}{\text { Area } \times \text { time }}$ $\therefore \quad \text { Intensity } \propto \mathrm{E} \propto \frac{1}{\lambda} \quad\left(\because \mathrm{E}=\frac{\mathrm{hc}}{\lambda}\right)$ For photoelectric effect- $\mathrm{I}=$ photoelectric current $\mathrm{I} \propto \text { energy } \propto \frac{1}{\lambda}$ $\mathrm{I} \propto \frac{1}{\lambda}$
AIIMS-2017
Dual nature of radiation and Matter
142231
Assertion: Threshold frequency depends on material of metal used. Reason: Threshold wavelength $\propto$ Threshold frequency.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
C Threshold frequency depends on material of metal used for most metal like zinc, Cadmium, magnesium, threshold frequency lie in ultraviolet region Threshold frequency is inversely proportional to threshold wavelength. $v \propto \frac{1}{\lambda}$
142236
If the photoelectric work function for a metallic surface is $4.125 \mathrm{eV}$, the cut-off wavelength for photoelectric phenomenon for the surface is
142237
An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be-
1 $\frac{24 \mathrm{hR}}{25 \mathrm{~m}}$
2 $\frac{25 \mathrm{hR}}{24 \mathrm{~m}}$
3 $\frac{24 \mathrm{~m}}{25 \mathrm{hR}}$
4 $\frac{25 \mathrm{~m}}{24 \mathrm{hR}}$
Explanation:
A Wavelength observed from transition of $n_{1}$ to $\mathrm{n}_{2}$. $\frac{1}{\lambda}=\mathrm{RZ}^{2}\left[\frac{1}{\mathrm{n}_{1}^{2}}-\frac{1}{\mathrm{n}_{2}^{2}}\right]$ $\mathrm{n}_{1}=1, \mathrm{n}_{2}=5, \mathrm{Z}=1$ $\frac{1}{\lambda}=\mathrm{R}\left[1-\frac{1}{5^{2}}\right]$ $\frac{1}{\lambda}=\frac{24}{25} \mathrm{R}$ Apply momentum conservation Momentum of photon $=$ Momentum of atom. $\frac{\mathrm{h}}{\lambda}=\mathrm{mv}$ $\mathrm{v}=\frac{\mathrm{h}}{\mathrm{m} \lambda}=\frac{\mathrm{h}}{\mathrm{m}} \times \frac{24}{25} \mathrm{R}$ $\mathrm{v}=\frac{24 \mathrm{hR}}{25 \mathrm{~m}}$
BCECE-2017
Dual nature of radiation and Matter
142238
The anode voltage of a photocell is kept fixed. The wavelength $\lambda$ of the light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows
1
2
3
4
Explanation:
D We know that, $\quad \text { Intensity }=\frac{\text { Power }}{\text { Area }}=\frac{\text { Energy }}{\text { Area } \times \text { time }}$ $\therefore \quad \text { Intensity } \propto \mathrm{E} \propto \frac{1}{\lambda} \quad\left(\because \mathrm{E}=\frac{\mathrm{hc}}{\lambda}\right)$ For photoelectric effect- $\mathrm{I}=$ photoelectric current $\mathrm{I} \propto \text { energy } \propto \frac{1}{\lambda}$ $\mathrm{I} \propto \frac{1}{\lambda}$
AIIMS-2017
Dual nature of radiation and Matter
142231
Assertion: Threshold frequency depends on material of metal used. Reason: Threshold wavelength $\propto$ Threshold frequency.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
C Threshold frequency depends on material of metal used for most metal like zinc, Cadmium, magnesium, threshold frequency lie in ultraviolet region Threshold frequency is inversely proportional to threshold wavelength. $v \propto \frac{1}{\lambda}$
142236
If the photoelectric work function for a metallic surface is $4.125 \mathrm{eV}$, the cut-off wavelength for photoelectric phenomenon for the surface is
142237
An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be-
1 $\frac{24 \mathrm{hR}}{25 \mathrm{~m}}$
2 $\frac{25 \mathrm{hR}}{24 \mathrm{~m}}$
3 $\frac{24 \mathrm{~m}}{25 \mathrm{hR}}$
4 $\frac{25 \mathrm{~m}}{24 \mathrm{hR}}$
Explanation:
A Wavelength observed from transition of $n_{1}$ to $\mathrm{n}_{2}$. $\frac{1}{\lambda}=\mathrm{RZ}^{2}\left[\frac{1}{\mathrm{n}_{1}^{2}}-\frac{1}{\mathrm{n}_{2}^{2}}\right]$ $\mathrm{n}_{1}=1, \mathrm{n}_{2}=5, \mathrm{Z}=1$ $\frac{1}{\lambda}=\mathrm{R}\left[1-\frac{1}{5^{2}}\right]$ $\frac{1}{\lambda}=\frac{24}{25} \mathrm{R}$ Apply momentum conservation Momentum of photon $=$ Momentum of atom. $\frac{\mathrm{h}}{\lambda}=\mathrm{mv}$ $\mathrm{v}=\frac{\mathrm{h}}{\mathrm{m} \lambda}=\frac{\mathrm{h}}{\mathrm{m}} \times \frac{24}{25} \mathrm{R}$ $\mathrm{v}=\frac{24 \mathrm{hR}}{25 \mathrm{~m}}$
BCECE-2017
Dual nature of radiation and Matter
142238
The anode voltage of a photocell is kept fixed. The wavelength $\lambda$ of the light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows
1
2
3
4
Explanation:
D We know that, $\quad \text { Intensity }=\frac{\text { Power }}{\text { Area }}=\frac{\text { Energy }}{\text { Area } \times \text { time }}$ $\therefore \quad \text { Intensity } \propto \mathrm{E} \propto \frac{1}{\lambda} \quad\left(\because \mathrm{E}=\frac{\mathrm{hc}}{\lambda}\right)$ For photoelectric effect- $\mathrm{I}=$ photoelectric current $\mathrm{I} \propto \text { energy } \propto \frac{1}{\lambda}$ $\mathrm{I} \propto \frac{1}{\lambda}$
AIIMS-2017
Dual nature of radiation and Matter
142231
Assertion: Threshold frequency depends on material of metal used. Reason: Threshold wavelength $\propto$ Threshold frequency.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
C Threshold frequency depends on material of metal used for most metal like zinc, Cadmium, magnesium, threshold frequency lie in ultraviolet region Threshold frequency is inversely proportional to threshold wavelength. $v \propto \frac{1}{\lambda}$
