Laser & Atomic Structure

Laser & Atomic Structure : The physics of an atom laser is similar to that of an optical laser. The main differences between an optical and an atom laser are that atoms interact with themselves, cannot be created as photons can, and possess mass whereas photons do not (atoms therefore propagate at a speed below that of light).

Laser & Atomic Structure

Q. Laser-

Ans. Is highly coherent

Q. A laser produce intense monochromatic, coherent light by which of the following process?

Ans. Stimulated emission

Q. When atom are held together by the sharing of valance electrons-

Ans. They from a covalent bond

Q. The diameter of an atom is-

Ans. 10^-6

Q. Which of the following element has lowest atomic number?

Ans. B

Q. Which of the following element does not occur in third group of periods table?

Ans. Helium

Q. The atomic number of silicon is 14. It can be therefore concluded that-

Ans. A silicon atom contains 14 protons

Q. If the atomic number of germanium is 32, the number of electrons in the outer most shell will be-

Ans. 4

Q. Which of the following elements does not have three valance electrons?

Ans. Phosphorus

Q. Which of the following elements does not have five valance electrons?

Ans. Indium

Q. Which of the following elements has for valance electrons?

Ans. Silicon, Germanium

Q. The total energy of an electron in an atom will be maximum when it is?

Ans. In an orbit farthest from the nucleus.

Q. Which of the following elements has for valance electron?

Ans. Silicon

Q. A germanium atom has-

Ans. Two electronic orbits

Q. One electron volt is equivalent to-

Ans. 1.6×10^-19 joule

Q. In case of selenium under the influence of varying light intensity-

Ans. Electrical conductivity changes

Q. In case of photo emission?

Ans. The maximum velocity of emission varies linearly with the frequency of incident

Q. The work function of a photo surface whose threshold wave length is 12,000 A will be-

Ans. 1.03 eV

Q. The minimum frequency at which the emission from a photo sensitive surface begins is called-

Ans. Threshold frequency

Q. In photo electric emission the time lag between the exposure of surface to light and the emission of electrons is less then-

Ans. 3×10^-9 second

Q. The photo electric current in amperes per watt of incident light depends on-

Ans. Frequency of incident light

Q. Which of the following statement about the photoelectric emission is incorrect?

Ans. Maximum velocity of emission varies with the intensity of light

Q. “A potential difference is developed across a current carrying metal strip when the strip is placed in a transverse magnetic field” the above effect is called-

Ans. Hall’s effect

Q. The crystal structure of silicon is-

Ans. Diamond

Q. The minimum charge carried by an anion is-

Ans. Equal to the charge of electron

Q. Which photo conductor is commonly used?

Ans. CdS

Q. A solar cell is example of-

Ans. Photo voltaic cell

Q. Which of the following is not electromagnetic in nature?

Ans. Cathode rays

Q. When light is directed at the metal surface the emitted electrons?

Ans. Have energies that depend upon frequency of light

Q. When yellow light is incident on a surface on electrons are emitted while green light can emit. if red light in incident on the surface, then

Ans. No electrons are emitted