Hertz's Observations

Q.

Which of these models explain how the free electrons are present in a metal?

1. Solar system model

2. Electron sea model

3. Quantum mechanical model

4. Plum pudding model Electrons are stuck in a positive sphere like plum in a cake

   

Q.

An external electric field is applied on a metal plate, high enough to force the electrons to eject out of the surface. Is this an example of Photo electric effect?

1. False

2. True

Q.

Why were electrons coming out from a metal when it was kept under a light source?

1. Light is a form of energy. The free electrons in the metal when get sufficient energy from light, they jump out of the metal

2. Light has negative charge. When it falls on an electron it makes it more negatively charged and they jump out of the metal by repelling other electrons.

3. God told electrons "Thou shalt leave the metal, whenever light falls unto thee" and so they come out

4. Light is an EM wave so when it falls on the metal surface its electric field pulls the electrons towards the source of light

Q. model explains how the free electrons are present in a metal.

1. Plum pudding
2. Solar system
3. Electron sea
4. Quantum mechanics

Q. When the free electrons in the metal gets sufficient energy from a light source, they jump out of the metal.

1. True
2. False

Q. The property of eye which is used in cinematography?

1. Range of vision
2. Persistance of vision
3. Power of accomodation
4. Colour of blindness

Q. What does the photoelectric effect demonstrate?

1. The particulate nature of light
2. The wave nature of light
3. The diffuse reflection of light
4. The total internal reflection of light
5. The polarization of light

Q. If a surface has a work function $4.0eV$, what is the maximum velocity of electrons liberated from the surface when it is irradiated with ultraviolet radiation of wavelength $0.2\mu m$?

1. $4.4\times {10}^{5}m/s$
2. $8.8\times {10}^{7}m/s$
3. $8.8\times {10}^{5}m/s$
4. $4.4\times {10}^{7}m/s$

Q. Choose the correct statement out of the following

1. Only a charged particle in motion is accompanied by matter waves.
2. Any particle, whether at rest or in motion is ever accompanied by matter waves.
3. Any particle in motion, whether charged or uncharged, is accompanied by matter waves.
4. Only subatomic particles in motion are accompanied by matter waves.

Q. Mark the correct statement: In photo electric effect-

1. electrons are emitted from metal surface when light falls on it.
2. the kinetic energy of photo electrons is more for light of longer wavelength in composition to that due to shorter wavelength.
3. both of the above
4. none of the above