Advertisements
Advertisements
प्रश्न
Why do Free electrons not leave the metal surface on their own
Advertisements
उत्तर
Free electrons cannot leave the metal surface on their own because they do not have sufficient kinetic energy.
APPEARS IN
संबंधित प्रश्न
Answer the following questions based on a hot cathode ray tube.
State the approximate voltage used to heat the filament
Under which conditions does the nucleus of an atom tend to radioactive?
Radiations given out from a source when subjected to an electric field in a direction perpendicular to their path are shown below in the diagram. The arrows show the path of the radiation A, B and C. Answer the following questions in terms of A, B and C.
1) Name the radiation B which is unaffected by the electrostatic field.
2) Why does the radiation C deflect more than A?
3) Which among the three causes the least biological damage externally.
4) Name the radiation which is used in carbon dating.
What happens to the mass number of an element when (i) an α -particle, (ii) a β -particle, and (iii) γ -radiation is emitted?
In the following fig. shows a radioactive source S in a thick lead container. The radiations pass through an electric field between the plates P and Q. Complete the diagram to show the paths of α , β and γ radiations.
Why is the source S placed in a thick lead container?
Radioactive substances were found to give off three types of rays. Name them. How do they
(a) React to the magnetic field?
(b) React to the electric field?
(c) Act when different thickness of lead sheets is placed in their path?
What are cathode rays? Why are they called ‘cathode rays’? Name a material which exhibits fluorescence when cathode rays fall on it.
A certain nucleus has a mass number 20 and atomic number 9. Find the number of neutrons and protons present in it.
Calculate the time interval between 33% decay and 67% decay if half-life of a substance is 20 minutes.
