Photoelectric Effect

Q.

According to the experiment of photoelectric effect, the number of electrons ejected from the metal surface is proportional to the intensity or brightness of light.

1. False

2. True

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. 1.99 x 10^-19 J

2. 2.99 x 10¹⁹ J

3. 3.99 x 10^-19 J

4. 4.99 x 10^-19 J

Q. Find the ratio of frequencies of violet light $({\lambda }_1=4.10\times {10}^{-5}cm)$ to that of red light $({\lambda }_2=6.56\times {10}^{-5}cm)$. Also determine the ratio of energies carried by them.

1. 2 : 1

2. 1 : 2

3. 1.6 : 1

4. 2.3 : 1

Q.

The kinetic energy of an electron is $4.55\times {10}^{-25}J$. The mass ofelectron is $9.1\times {10}^{-31}kg$. Calculate velocity of the electron.

1. 10 ms^-1

2. 10² ms^-1

3. 10⁴ ms^-1

4. 10³ ms^-1

Q.

A Light of wavelength $\lambda$ shines on a metal surface with intensity X, and the metal emits Y electrons per second of average energy Z. What will happen to Y and Z If X is doubled?

1. Y will be doubled and Z will become half.

2. Y will remain same and Z will be doubled.

3. Both Y and Z will be doubled.

4. Y will be doubled but Z will remain same.

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 v₀, the kinetic energy of the electrons ejected is zero.

2. If the frequency of the incident radiation is v, the kinetic energy of the electrons ejected will be hv - hv₀.

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

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

Q. Threshold frequency of a metal is $f_0$. When light of frequency $2f_0$ is incident on the metal plate, maximum velocity of electron emitted is $v_1$. When frequency of incident radiation is $5f_0$, maximum velocity of emitted electron is $v_2$. The ratio of $\frac{v_1}{v_2}$ is

1. $1:4$
2. $2:3$
3. $1:2$
4. $3:5$

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.

When a certain metal was irradiated with light of frequency $1.6\times {10}^{16}Hz$, the photoelectrons emitted had twice the kinetic energy as the photoelectrons emitted when the same metal was irradiated with light of frequency $1.0\times {10}^{16}Hz$. Calculate the threshold frequency ($v_0$) for the metal.

1. 2 x 10¹⁵ Hz

2. 6 x 10¹⁵ Hz

3. 12 x 10¹⁵ Hz

4. 4 x 10¹⁵ Hz

Q.

Which of the following explains the particle like nature?

1. Black Body Radiation

2. Photoelectric effect

3. Diffraction

4. None of these