Photoelectric Effect

Q. The potential energy of an electron in the hydrogen atom is –6.8 eV. Indicate in which excited state, the electron is present.

1. First
2. second
3. Third
4. Fourth

Q. How does the intensity of the incident radiation affect photoelectric effect?

1. As the intensity increases, photoelectric effect may increase
2. As the intensity increases, photoelectric effect decreases.
3. As the intensity decreases, photoelectric effect increases.
4. No effect

Q.

A photon of 300 nm is absorbed by a gas, which then re-emits two photons. One re-emitted photon has a wavelength of 400 nm. Calculate the energy of the other photon re-emitted out.

1. $16.56\times {10}^{-18}J$

2. $16.56\times {10}^{-12}J$

3. $16.56\times {10}^{-20}J$

4. $16.56\times {10}^{-15}J$

Q.

If the threshold frequency of a metal for photoelectric effect is $v_0$, then which of the following will not happen?

1. If the frequency of the incident radiation is , the kinetic energy of the electrons ejected will be - .

2. If the frequency is kept sameat but intensity is increased, the number of electrons ejected will increase.

3. If the frequency of incident radiation is further increased, the number of photoelectrons ejected will increase.

4. If the frequency of the incident radiation is , the kinetic energy of the electrons ejected is zero.

Q.

Which of the following explains the particle like nature?

1. Black Body Radiation

2. Photoelectric effect

3. Diffraction

4. None of these

Q.

The longest wavelength doublet absorption transition is observed at 589 and 589.6 nm. Calculate the frequency of each transition and energy difference between two excited states.

Q.

Which alkali metal does not exhibit photoelectric effect:

1. Lithium

2. Potassium

3. Cesium

4. Sodium

Q.

How does wavelength affect photoelectric effect?

Q. The number of photons of wavelength 400 nm emitted from 10W electric bulb for 10 sec is

1. 2.01 X 10²³

2. 2.01 X 10²⁰

3. 2 X 10²²

4. 10²⁰

Q.

Dual behaviour of matter proposed by de Broglie led to the discovery of electron microscope often used for the highly magnified images of biological molecules and other type of material. If the velocity of the electron in this microscope is 1.6 × 10⁶ ms^–1, calculate de Broglie wavelength associated with this electron.

Q. 4 Chlorophyll is a biomolecule responsible for green 15colour in the plants. Chlorophyll contains 2.68% ofmagnesium by mass. Calculate the number ofmagnesium atoms in 6 g of chlorophyll (Mg- 24)

Q. The frequency associated with photon of radiation having a wavelength of $6000A^0$ is

1. 5 X 10¹⁴ Hz

2. 5 X 10¹⁰ Hz

3. 2 X 10¹⁴ Hz

4. 5 X 10¹⁵ Hz

Q. Which out of the following can explain the photoelectric emission?

1. Wave nature of light
2. Particle nature of light
3. Dual nature of light
4. None of this

Q. 37. An excited state of doubly joined Lithium (Li2+) has an orbital radius that is about 1.33 times that of the ground state of hydrogen H in(Bohrs theory).The ratio of energy of the two states , E(Li2+)/E(H) is A)2.25 .B)4.5 C)1 D)9

Q.

The threshold frequency ${\nu }_0$ for a metal is $7.0\times {10}^{14}{s}^{-1}$. Calculate the kinetic energy of an electron emitted when radiation of frequency $\nu$ = $1.0\times {10}^{15}{s}^{-1}$

1. 2.99 x 10¹⁹ J

2. 3.99 x 10^-19 J

3. 4.99 x 10^-19 J

4. 1.99 x 10^-19 J

Q. Which of the graphs shown below does not represent the relationship between incident light and the electron ejected from the metal surface?

1. 
2. 
3. 
4. 

Q. When radiation of certain wavelength shines on the cathode of the photoelectric cell, the photocurrent produced can be reduced to zero by applying stopping potential of 3 V. If the workfunction of the photo emitter is 3.63 eV, find the frequency of radiation

1. $3.2\times {10}^{15}$ Hz
2. $1.6\times {10}^{15}$ Hz
3. $1.6\times {10}^{12}$ Hz
4. $3.2\times {10}^{12}$ Hz

Q. Work function of a metal is 3eV. An electromagnetic radiation of 200 nm is incident on metal surface, calculate the maximum speed of photoelectrons ejected. (Take the value of h= $6.6\times {10}^{-34}Js)$

1. $2.05\times {10}^{6}m/s$
2. $1.75\times {10}^{6}m/s$
3. $1.05\times {10}^{6}m/s$
4. $2.20\times {10}^{6}m/s$

Q.

The work function of a metal is 4.2 $eV$. If a radiation of $2000\stackrel{o}{A}$ falls on the metal, then the kinetic energy of the fastest photoelectron is:

1. $1.6\times {10}^{-19}J$

2. $16\times {10}^{-10}J$

3. $3.2\times {10}^{-19}J$

4. $6.4\times {10}^{-10}J$

Q. A radiation of wavelength $3000A^{\circ }$ falls on a photoelectric surface of work function 1.6 eV. What is the stopping potential of the emitted electron?

1. 3.52 V
2. 2.53 V
3. 1.50 V
4. 3.32 V

Q. 41 The ratio of difference in wavelength of 1st and 2nd line of lyman series in H-like atom to difference in wavelength for 2nd and 3rd lines of same series is

Q.

According to Einstein photoelectric effect equation, the graph between the kinetic energy of photoelectron ejected and the frequency ($\nu$) of incidented radiations is:

1. 

2. 

3. 

4. 

Q. What is the difference between the state functions and state variables in Thermodynamics ?

Q. cobalt exhibits hcp structure at room temperatur

Q.

According to Einstein photoelectric effect equation, the graph between the kinetic energy of photoelectron ejected and the frequency ($\nu$) of incidented radiations is:

1. 

2. 

3. 

4. 

Q.

A gas absorbs a photon of 355 nm and emits at two wavelengths. If one of the emissions is at 680 nm, the other is at

1. 1035 nm

2. 325 nm

3. 743 nm

4. 518 nm

Q. For the photoelectric effect in sodium, the figure shows the plot of cut-off voltage versus frequency of incident radiation.
The threshold frequency is:

1. $6.5\times {10}^{14}Hz$
2. $4.5\times {10}^{14}Hz$
3. $3\times {10}^{14}Hz$
4. $5\times {10}^{14}Hz$

Q.
The threshold frequency of a metal is $6\times {10}^{14}{s}^{-1}$. Calculate the kinetic energy of an electron emitted when radiation of frequency $1.1\times {10}^{15}{s}^{-1}$ hits the metal.

1. $3.31\times {10}^{-19}$ J
2. $1.13\times {10}^{-18}$ J
3. $7.12\times {10}^{-19}$ J
4. None of These

Q. When an electromagnetic radiation of wavelength $310nm$ falls on the surface of sodium metal, electrons are emitted with $K.E_{max}=1.5eV$. Determine the work function $W_o$ of metal.

1. $2.5eV$
2. $5.2eV$
3. $10.5eV$
4. $12.5eV$

Q. A light of wavelength $\lambda$ falls on a metal having work function $W=hc/{\lambda }_0$. The photoelectric effect will take place only if:

1. $\lambda \ge {\lambda }_0$
2. $\lambda \ge 2{\lambda }_0$
3. $\lambda \le {\lambda }_0$
4. $\lambda \ge {\lambda }_0/2$