357820
If mean wavelength of light radiated by 100 \(W\) lamp is 5000 \( \mathop A^{~~\circ} \), the number of photons radiated per second would be
1 \({2.5 \times 10^{20}}\)
2 \({2.5 \times 10^{22}}\)
3 \({3 \times 10^{23}}\)
4 \({5 \times 10^{17}}\)
Explanation:
Power of the lamp \({=100 {~W}}\) Energy radiated by the lamp in one second \({=100 {~J}}\) Energy of the emitted light with wavelength \({\lambda}\), \(\begin{align*}& E=\dfrac{h c}{\lambda} \\& E=\dfrac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{5000 \times 10^{-10}}=3.96 \times 10^{-19} {~J}\end{align*}\) Number of photons emitted \({=\dfrac{100 {~J}}{3.96 \times 10^{-19} {~J}}}\) \({=0.2525 \times 10^{21}=2.5 \times 10^{20}}\). So correct option is (1)
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357821
Photoelectric effect supports the quantum nature of light because
1 There is minimum frequency of light above which no photo electrons are emitted
2 The maximum kinetic energy of photo electrons depends on both frequency and intensity of light
3 Even when a metal surface is faintly illuminated, the photoelectrons do not leave the surface immediately
4 The maximum \(K.E\). of photo electrons depends only on the frequency of light and not on intensity
Explanation:
Conceptual Question
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357822
Statement A : Photoelectric effect supports the quantum nature of light. Statement B : Photoelectric emission is instantaneous.
1 Statement A is correct but Statement B is incorrect.
2 Statement A is incorrect but Statement B is correct.
3 Both statements are correct.
4 Both Statements are incorrect.
Explanation:
Photoelectric effect is observed only when the frequency of the incident radiation is more than a characteristic value depending upon the metal. Small amount of energy given slowly over a long time does not liberate photoelectrons. Thus photoelectric emission is an instantaneous process. So option (3) is correct.
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357823
Assertion : The threshold frequency of photoelectric effect supports the particle nature of light. Reason : If frequency of incident light is iess than the threshold frequency, electrons are emitted from metal surface.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
In the photoelectric effect, photoelectrons are emitted only when the frequency of incident light exceeds a specific threshold, irrespective of light intensity. It is as per Einstein equation \(h v=h v_{0}+\dfrac{1}{2} m v_{\max }^{2}\). So correct option is (3).
357820
If mean wavelength of light radiated by 100 \(W\) lamp is 5000 \( \mathop A^{~~\circ} \), the number of photons radiated per second would be
1 \({2.5 \times 10^{20}}\)
2 \({2.5 \times 10^{22}}\)
3 \({3 \times 10^{23}}\)
4 \({5 \times 10^{17}}\)
Explanation:
Power of the lamp \({=100 {~W}}\) Energy radiated by the lamp in one second \({=100 {~J}}\) Energy of the emitted light with wavelength \({\lambda}\), \(\begin{align*}& E=\dfrac{h c}{\lambda} \\& E=\dfrac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{5000 \times 10^{-10}}=3.96 \times 10^{-19} {~J}\end{align*}\) Number of photons emitted \({=\dfrac{100 {~J}}{3.96 \times 10^{-19} {~J}}}\) \({=0.2525 \times 10^{21}=2.5 \times 10^{20}}\). So correct option is (1)
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357821
Photoelectric effect supports the quantum nature of light because
1 There is minimum frequency of light above which no photo electrons are emitted
2 The maximum kinetic energy of photo electrons depends on both frequency and intensity of light
3 Even when a metal surface is faintly illuminated, the photoelectrons do not leave the surface immediately
4 The maximum \(K.E\). of photo electrons depends only on the frequency of light and not on intensity
Explanation:
Conceptual Question
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357822
Statement A : Photoelectric effect supports the quantum nature of light. Statement B : Photoelectric emission is instantaneous.
1 Statement A is correct but Statement B is incorrect.
2 Statement A is incorrect but Statement B is correct.
3 Both statements are correct.
4 Both Statements are incorrect.
Explanation:
Photoelectric effect is observed only when the frequency of the incident radiation is more than a characteristic value depending upon the metal. Small amount of energy given slowly over a long time does not liberate photoelectrons. Thus photoelectric emission is an instantaneous process. So option (3) is correct.
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357823
Assertion : The threshold frequency of photoelectric effect supports the particle nature of light. Reason : If frequency of incident light is iess than the threshold frequency, electrons are emitted from metal surface.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
In the photoelectric effect, photoelectrons are emitted only when the frequency of incident light exceeds a specific threshold, irrespective of light intensity. It is as per Einstein equation \(h v=h v_{0}+\dfrac{1}{2} m v_{\max }^{2}\). So correct option is (3).
357820
If mean wavelength of light radiated by 100 \(W\) lamp is 5000 \( \mathop A^{~~\circ} \), the number of photons radiated per second would be
1 \({2.5 \times 10^{20}}\)
2 \({2.5 \times 10^{22}}\)
3 \({3 \times 10^{23}}\)
4 \({5 \times 10^{17}}\)
Explanation:
Power of the lamp \({=100 {~W}}\) Energy radiated by the lamp in one second \({=100 {~J}}\) Energy of the emitted light with wavelength \({\lambda}\), \(\begin{align*}& E=\dfrac{h c}{\lambda} \\& E=\dfrac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{5000 \times 10^{-10}}=3.96 \times 10^{-19} {~J}\end{align*}\) Number of photons emitted \({=\dfrac{100 {~J}}{3.96 \times 10^{-19} {~J}}}\) \({=0.2525 \times 10^{21}=2.5 \times 10^{20}}\). So correct option is (1)
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357821
Photoelectric effect supports the quantum nature of light because
1 There is minimum frequency of light above which no photo electrons are emitted
2 The maximum kinetic energy of photo electrons depends on both frequency and intensity of light
3 Even when a metal surface is faintly illuminated, the photoelectrons do not leave the surface immediately
4 The maximum \(K.E\). of photo electrons depends only on the frequency of light and not on intensity
Explanation:
Conceptual Question
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357822
Statement A : Photoelectric effect supports the quantum nature of light. Statement B : Photoelectric emission is instantaneous.
1 Statement A is correct but Statement B is incorrect.
2 Statement A is incorrect but Statement B is correct.
3 Both statements are correct.
4 Both Statements are incorrect.
Explanation:
Photoelectric effect is observed only when the frequency of the incident radiation is more than a characteristic value depending upon the metal. Small amount of energy given slowly over a long time does not liberate photoelectrons. Thus photoelectric emission is an instantaneous process. So option (3) is correct.
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357823
Assertion : The threshold frequency of photoelectric effect supports the particle nature of light. Reason : If frequency of incident light is iess than the threshold frequency, electrons are emitted from metal surface.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
In the photoelectric effect, photoelectrons are emitted only when the frequency of incident light exceeds a specific threshold, irrespective of light intensity. It is as per Einstein equation \(h v=h v_{0}+\dfrac{1}{2} m v_{\max }^{2}\). So correct option is (3).
357820
If mean wavelength of light radiated by 100 \(W\) lamp is 5000 \( \mathop A^{~~\circ} \), the number of photons radiated per second would be
1 \({2.5 \times 10^{20}}\)
2 \({2.5 \times 10^{22}}\)
3 \({3 \times 10^{23}}\)
4 \({5 \times 10^{17}}\)
Explanation:
Power of the lamp \({=100 {~W}}\) Energy radiated by the lamp in one second \({=100 {~J}}\) Energy of the emitted light with wavelength \({\lambda}\), \(\begin{align*}& E=\dfrac{h c}{\lambda} \\& E=\dfrac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{5000 \times 10^{-10}}=3.96 \times 10^{-19} {~J}\end{align*}\) Number of photons emitted \({=\dfrac{100 {~J}}{3.96 \times 10^{-19} {~J}}}\) \({=0.2525 \times 10^{21}=2.5 \times 10^{20}}\). So correct option is (1)
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357821
Photoelectric effect supports the quantum nature of light because
1 There is minimum frequency of light above which no photo electrons are emitted
2 The maximum kinetic energy of photo electrons depends on both frequency and intensity of light
3 Even when a metal surface is faintly illuminated, the photoelectrons do not leave the surface immediately
4 The maximum \(K.E\). of photo electrons depends only on the frequency of light and not on intensity
Explanation:
Conceptual Question
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357822
Statement A : Photoelectric effect supports the quantum nature of light. Statement B : Photoelectric emission is instantaneous.
1 Statement A is correct but Statement B is incorrect.
2 Statement A is incorrect but Statement B is correct.
3 Both statements are correct.
4 Both Statements are incorrect.
Explanation:
Photoelectric effect is observed only when the frequency of the incident radiation is more than a characteristic value depending upon the metal. Small amount of energy given slowly over a long time does not liberate photoelectrons. Thus photoelectric emission is an instantaneous process. So option (3) is correct.
PHXII11:DUAL NATURE OF RADIATION AND MATTER
357823
Assertion : The threshold frequency of photoelectric effect supports the particle nature of light. Reason : If frequency of incident light is iess than the threshold frequency, electrons are emitted from metal surface.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
In the photoelectric effect, photoelectrons are emitted only when the frequency of incident light exceeds a specific threshold, irrespective of light intensity. It is as per Einstein equation \(h v=h v_{0}+\dfrac{1}{2} m v_{\max }^{2}\). So correct option is (3).
