Q 1. What is the Kinetic energy of the photoelectrons ejected from a tungsten surface by UV light of wavelength 1940Å ? Express the result in eV. The photoelectric threshold of tungsten is 2300Å .
Ans. K=1 eV
Q 2. The work function of sodium is 2 eV.
(a) Find the maximum energy of the photoelectrons ejected when a sodium surface is illuminated with light of 3105Å.
(b) Calculate the maximum wavelength of the light that would produce photoelectric effect.
Ans. 2 eV , 6210Å
Q 3. A small plate of metal (work function 1.17 eV) is placed at a distance 2 m from monochromatic light source of wavelength 4.8x10-7and power 1.0 watt. The light falls normally on plate. Find the number of photons striking the metal plate per square meter per second. If a constant uniform magnetic field of strength 10-4 tesla is applied parallel to the metal surface , find the radius of the largest circular path followed by the emitted photoelectrons.
Ans. 4.82 x1016 , 4.0 cm
Q 4. Calculate the wavelength of the wave associated with :
(a) 1 MeV photon
(b) 1 MeV proton
Ans. 1.242x10-10 cm, 2.84x10-12 cm
Q 5. The molecules of a certain gas at 320 K have a rms speed of .499 Km/sec. Calculate the De Brogli wavelength of these molecules. What is the gas?
Ans. 0.25Å , O16
Class 9 physics notes on chapter motion is now available at the following link CLASS 9 MOTION NOTES (FULL LENGTH)
Question1: A charge Q is divided in two parts q and Q - q separated by a distance R. If force between the two charges is maximum, find the ...
Coherent sources are those sources of light which emit continous light waves of same wavelength , same frequency and are in same phase or h...
Our New Free physics ebooks (pdfs) are available at this link . Hope you lile them.
Unit I: Physical World and Measurement (Periods 10) Physics: Scope and excitement; nature of physical laws; Physics, technology and society...
ADVANTAGES The generation of A.C. is cheaper than that of D.C. A.C. machines are simple , robust and do mot require much attention for the...
Hi all here in this article i am giving some tips and tricks to solve problems in mechanics. To master problem solving skill you need to pra...
1.A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement x i...
Many times i have had users ask me a question which book to opt between H.C Verma Concepts of physics and NCERT physics books . My answer ...
Unit I: Electrostatics (Periods 25) Electric charges and their conservation. Coulomb’s law – force between two point charges, forces betwee...