QBManager

Dual nature of radiation and Matter

142236 If the photoelectric work function for a metallic surface is $4.125 eV$ , the cut-off wavelength for photoelectric phenomenon for the surface is

1

4500 \AA

2

1700 \AA

3

2800 \AA

4

3000 \AA

Explanation:

D Given that,
$ϕ_{o} = 4.125 eV = 4.125 \times 1.6 \times 10^{- 19} J$
$h = 6.6 \times 10^{- 34} JS$
$c = 3 \times 10^{8} m / s$
Work function-
$ϕ_{o} = \frac{hc}{λ_{o}}$
$λ_{o} = \frac{6.6 \times 10^{- 34} \times 3 \times 10^{8}}{4.125 \times 1.6 \times 10^{- 19}}$
$λ_{o} = 3000 ◻$

COMEDK-2017

Dual nature of radiation and Matter

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 hR}{25 m}

2

\frac{25 hR}{24 m}

3

\frac{24 m}{25 hR}

4

\frac{25 m}{24 hR}

Explanation:

A Wavelength observed from transition of $n_{1}$ to $n_{2}$ .
$\frac{1}{λ} = {RZ}^{2} [\frac{1}{n_{1}^{2}} - \frac{1}{n_{2}^{2}}]$
$n_{1} = 1, n_{2} = 5, Z = 1$
$\frac{1}{λ} = R [1 - \frac{1}{5^{2}}]$
$\frac{1}{λ} = \frac{24}{25} R$
Apply momentum conservation
Momentum of photon $=$ Momentum of atom.
$\frac{h}{λ} = mv$
$v = \frac{h}{m λ} = \frac{h}{m} \times \frac{24}{25} R$
$v = \frac{24 hR}{25 m}$

BCECE-2017

Dual nature of radiation and Matter

142238 The anode voltage of a photocell is kept fixed. The wavelength $λ$ 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,
$Intensity = \frac{Power}{Area} = \frac{Energy}{Area \times time}$
$∴ Intensity \propto E \propto \frac{1}{λ} (∵ E = \frac{hc}{λ})$
For photoelectric effect-
$I =$ photoelectric current
$I \propto energy \propto \frac{1}{λ}$
$I \propto \frac{1}{λ}$

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.
$v \propto \frac{1}{λ}$

AIIMS-26.052018(E)

Dual nature of radiation and Matter

142236 If the photoelectric work function for a metallic surface is $4.125 eV$ , the cut-off wavelength for photoelectric phenomenon for the surface is

1

4500 \AA

2

1700 \AA

3

2800 \AA

4

3000 \AA

Explanation:

D Given that,
$ϕ_{o} = 4.125 eV = 4.125 \times 1.6 \times 10^{- 19} J$
$h = 6.6 \times 10^{- 34} JS$
$c = 3 \times 10^{8} m / s$
Work function-
$ϕ_{o} = \frac{hc}{λ_{o}}$
$λ_{o} = \frac{6.6 \times 10^{- 34} \times 3 \times 10^{8}}{4.125 \times 1.6 \times 10^{- 19}}$
$λ_{o} = 3000 ◻$

COMEDK-2017

Dual nature of radiation and Matter

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 hR}{25 m}

2

\frac{25 hR}{24 m}

3

\frac{24 m}{25 hR}

4

\frac{25 m}{24 hR}

Explanation:

A Wavelength observed from transition of $n_{1}$ to $n_{2}$ .
$\frac{1}{λ} = {RZ}^{2} [\frac{1}{n_{1}^{2}} - \frac{1}{n_{2}^{2}}]$
$n_{1} = 1, n_{2} = 5, Z = 1$
$\frac{1}{λ} = R [1 - \frac{1}{5^{2}}]$
$\frac{1}{λ} = \frac{24}{25} R$
Apply momentum conservation
Momentum of photon $=$ Momentum of atom.
$\frac{h}{λ} = mv$
$v = \frac{h}{m λ} = \frac{h}{m} \times \frac{24}{25} R$
$v = \frac{24 hR}{25 m}$

BCECE-2017

Dual nature of radiation and Matter

142238 The anode voltage of a photocell is kept fixed. The wavelength $λ$ 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,
$Intensity = \frac{Power}{Area} = \frac{Energy}{Area \times time}$
$∴ Intensity \propto E \propto \frac{1}{λ} (∵ E = \frac{hc}{λ})$
For photoelectric effect-
$I =$ photoelectric current
$I \propto energy \propto \frac{1}{λ}$
$I \propto \frac{1}{λ}$

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.
$v \propto \frac{1}{λ}$

AIIMS-26.052018(E)

Dual nature of radiation and Matter

142236 If the photoelectric work function for a metallic surface is $4.125 eV$ , the cut-off wavelength for photoelectric phenomenon for the surface is

1

4500 \AA

2

1700 \AA

3

2800 \AA

4

3000 \AA

Explanation:

D Given that,
$ϕ_{o} = 4.125 eV = 4.125 \times 1.6 \times 10^{- 19} J$
$h = 6.6 \times 10^{- 34} JS$
$c = 3 \times 10^{8} m / s$
Work function-
$ϕ_{o} = \frac{hc}{λ_{o}}$
$λ_{o} = \frac{6.6 \times 10^{- 34} \times 3 \times 10^{8}}{4.125 \times 1.6 \times 10^{- 19}}$
$λ_{o} = 3000 ◻$

COMEDK-2017

Dual nature of radiation and Matter

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 hR}{25 m}

2

\frac{25 hR}{24 m}

3

\frac{24 m}{25 hR}

4

\frac{25 m}{24 hR}

Explanation:

A Wavelength observed from transition of $n_{1}$ to $n_{2}$ .
$\frac{1}{λ} = {RZ}^{2} [\frac{1}{n_{1}^{2}} - \frac{1}{n_{2}^{2}}]$
$n_{1} = 1, n_{2} = 5, Z = 1$
$\frac{1}{λ} = R [1 - \frac{1}{5^{2}}]$
$\frac{1}{λ} = \frac{24}{25} R$
Apply momentum conservation
Momentum of photon $=$ Momentum of atom.
$\frac{h}{λ} = mv$
$v = \frac{h}{m λ} = \frac{h}{m} \times \frac{24}{25} R$
$v = \frac{24 hR}{25 m}$

BCECE-2017

Dual nature of radiation and Matter

142238 The anode voltage of a photocell is kept fixed. The wavelength $λ$ 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,
$Intensity = \frac{Power}{Area} = \frac{Energy}{Area \times time}$
$∴ Intensity \propto E \propto \frac{1}{λ} (∵ E = \frac{hc}{λ})$
For photoelectric effect-
$I =$ photoelectric current
$I \propto energy \propto \frac{1}{λ}$
$I \propto \frac{1}{λ}$

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.
$v \propto \frac{1}{λ}$

AIIMS-26.052018(E)

Dual nature of radiation and Matter

142236 If the photoelectric work function for a metallic surface is $4.125 eV$ , the cut-off wavelength for photoelectric phenomenon for the surface is

1

4500 \AA

2

1700 \AA

3

2800 \AA

4

3000 \AA

Explanation:

D Given that,
$ϕ_{o} = 4.125 eV = 4.125 \times 1.6 \times 10^{- 19} J$
$h = 6.6 \times 10^{- 34} JS$
$c = 3 \times 10^{8} m / s$
Work function-
$ϕ_{o} = \frac{hc}{λ_{o}}$
$λ_{o} = \frac{6.6 \times 10^{- 34} \times 3 \times 10^{8}}{4.125 \times 1.6 \times 10^{- 19}}$
$λ_{o} = 3000 ◻$

COMEDK-2017

Dual nature of radiation and Matter

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 hR}{25 m}

2

\frac{25 hR}{24 m}

3

\frac{24 m}{25 hR}

4

\frac{25 m}{24 hR}

Explanation:

A Wavelength observed from transition of $n_{1}$ to $n_{2}$ .
$\frac{1}{λ} = {RZ}^{2} [\frac{1}{n_{1}^{2}} - \frac{1}{n_{2}^{2}}]$
$n_{1} = 1, n_{2} = 5, Z = 1$
$\frac{1}{λ} = R [1 - \frac{1}{5^{2}}]$
$\frac{1}{λ} = \frac{24}{25} R$
Apply momentum conservation
Momentum of photon $=$ Momentum of atom.
$\frac{h}{λ} = mv$
$v = \frac{h}{m λ} = \frac{h}{m} \times \frac{24}{25} R$
$v = \frac{24 hR}{25 m}$

BCECE-2017

Dual nature of radiation and Matter

142238 The anode voltage of a photocell is kept fixed. The wavelength $λ$ 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,
$Intensity = \frac{Power}{Area} = \frac{Energy}{Area \times time}$
$∴ Intensity \propto E \propto \frac{1}{λ} (∵ E = \frac{hc}{λ})$
For photoelectric effect-
$I =$ photoelectric current
$I \propto energy \propto \frac{1}{λ}$
$I \propto \frac{1}{λ}$

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.
$v \propto \frac{1}{λ}$

AIIMS-26.052018(E)

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