Enter Einstein!

Q.

By photoelectric effect, Einstein, proved

1. $E=hv$

2. $K.E.=\frac{1}{2}m{v}^2$

3. $E=m{c}^2$

4. $E=\frac{Rh{c}^2}{n^2}$

Q. Some of the most profound statements on the nature of science have come from Albert Einstein, one of the greatest scientists of all time. What do you think did Einstein mean when he said : "The most incomprehensible thing about the world is that it is comprehensible"?

Q.

Einstein's photoelectric equation states that $E_k=hv-\varphi$. In this equation $E_k$ refers to

1. Kinetic energy of all the emitted electrons

2. Mean kinetic energy of the emitted electrons

3. Maximum kinetic energy of the emitted electrons

4. Minimum kinetic energy of the emitted electrons

Q. When the light of frequency $2{\nu }_0$ (where ${\nu }_0$ is a threshold frequency) is incident on a metal plate, the maximum velocity of electrons emitted is $v_1$. When the frequency of the incident radiation is increased to $5{\nu }_0$, the maximum velocity of electrons emitted from the same plate is $v_2$. The ratio of $v_1$ to $v_2$ is

1. 1 : 2
2. 1 : 4
3. 4 : 1
4. 2 : 1

Q. The threshold frequency for a certain photosensitive metal is ${\nu }_0$. When it is illuminated by light of frequency $\nu =2{\nu }_0$, the maximum velocity of photoelectrons is $v_0$. What will be the maximum velocity of the photoelectrons when the same metal is illuminated b a light of frequency $\nu =5{\nu }_0$?

1. $\sqrt{2}{v}_0$
2. $2v_0$
3. $2\sqrt{2}{v}_0$
4. $4v_0$

Q.

If the threshold wavelength for sodium is $5420\stackrel{\circ }{A}$, then the work function of sodium is

1. 4.58 eV

2. 2.28 eV

3. 1.14 eV

4. 0.23 eV

Q.

The work function of a metal is

1. The energy for the electron to enter into the metal

2. The energy for producing X-ray

3. The energy for the electron to come out from metal surface

4. None of these

Q. According to the quantum theory of light, the light consists of the packets of energy, each packet is called as :

1. photon
2. proton
3. electron
4. atom

Q.

The work function for tungsten and sodium are 4.5 eV and 2.3 eV respectively. If the threshold wavelength $\lambda$ for sodium is $5460\stackrel{\circ }{A}$ the value of $\lambda$ for tungsten is

1. $5893\stackrel{\circ }{A}$

2. $10683\stackrel{\circ }{A}$

3. $2791\stackrel{\circ }{A}$

4. $528\stackrel{\circ }{A}$

Q.

The work function for tungsten and sodium are 4.5 eV and 2.3 eV respectively. If the threshold wavelength $\lambda$ for sodium is $5460\stackrel{\circ }{A}$ the value of $\lambda$ for tungsten is

1. $5893\stackrel{\circ }{A}$

2. $10683\stackrel{\circ }{A}$

3. $2791\stackrel{\circ }{A}$

4. $528\stackrel{\circ }{A}$