1. De-Broglie equation states the :
(A) dual nature
(B) particle nature
(C) wave nature
(D) none of these
| Answer ⇒ A |
2. Protons and alpha particles have the same de-Broglie wavelength. What is same for both of them ?
(A) Energy
(B) Time period
(C) Frequency
(D) Momentum
| Answer ⇒ D |
3. Kinetic energy of emitted electrons depends upon :
(A) frequency
(B) intensity
(C) nature of atmosphere surrounding the electrons
(D) none of these
| Answer ⇒ A |
4. De-Broglie wavelength of a body of mass m and kinetic energy E is given by (symbols have their usual meanings) :
| Answer ⇒ A |
5. The ratio of specific charge of an alpha particle to the proton is :
(A) 1:2
(B) 2:1
(C) 4:1
(D) 1:4
| Answer ⇒ A |
6. In photo electric emission, for alkali metals the threshold frequency lies in the :
(A) visible region
(B) ultraviolet region
(C) infrared region
(D) far end of the infrared region
| Answer ⇒ A |
7. Which of the following radiations cannot eject photo electrons ?
(A) ultraviolet
(B) infrared
(C) visible
(D) X-rays
| Answer ⇒ B |
8. What is the de-Broglie wavelength of an electron accelerated from rest through a potential difference of 100 volts ?
(A) 12.3 Å
(B) 1.23 Å
(C) 0.123 Å
(D) none of these
| Answer ⇒ B |
9. What is the de-Broglie wavelength of an electron accelerated from rest through a potential difference of V volts ?
| Answer ⇒ A |
10. What is the de-Broglie wavelength of a proton accelerated from rest through a potential difference of V volts ?
| Answer ⇒ D |
11. When a yellow light is incident on a surface, no electrons are emitted while green light can emit electrons. If the red light is incident on the surface then :
(A) no electrons are emitted
(B) photons are emitted
(C) electrons of higher energy are emitted
(D) electrons of lower energy are emitted
| Answer ⇒ A |
12. A metal surface ejects electrons when hit by green light but none when hit by yellow light. The electrons will be ejected when the surface is hit by :
(A) blue light
(B) heat rays
(C) infra-red light
(D) red light
| Answer ⇒ A |
13. Photoelectric effect can be caused by :
(A) X-rays
(B) Visible light
(C) ϒ-rays
(D) All of these
| Answer ⇒ D |
Class 12th physics objective question in English