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प्रश्न
What is meant by radioactivity?
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उत्तर
Elements with a high atomic number such as uranium, thorium, radium have a property of spontaneously emitting invisible, highly penetrating and high energy radiation. This property is called radioactivity. The nucleus of radioactive elements is unstable.
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संबंधित प्रश्न
Arrange α, β, and γ rays in ascending order with respect to their
1) Penetrating power.
2) Ionising power
3) Biological effect
In a cathode ray tube, what is the function of anode?
Represent the change in the nucleus of a radioactive element when a β particle is emitted.
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.
Give a scientific explanation.
When the radiation coming out from a certain radioactive substance is passed through an electric field, marks are found at three places on the photographic plate placed in its path.
State the penetrating range of α, β and γ radiations.
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?
Draw a diagram of a simple atom showing the nucleus and electrons. In this atom:
(a) What type of charge will there be on the nucleus?
(b) What is the value of this charge?
What is nucleus of an atom? Compare its size with that of the atom. Name its constitutents. How is the number of these constituents determined by the atomic number its atomic model.
A certain nucleus A (mass number 238 and atomic number 92) is radioactive and becomes a nucleus B (mass number 234 and atomic number 90) by the loss of one particle.
What particle was emitted?
During the emission of a beta particle, the ______ number remains same.
Define free electrons.
How is a cathode ray beam affected while passing through an electric field?
What are cathode rays? Why are they called ‘cathode rays’? Name a material which exhibits fluorescence when cathode rays fall on it.
How is a zinc sulphide screen affected when a cathode ray beam strikes it?
Why are materials of low work function preferred as thermionic cathode materials?
Name the three main parts of a Cathode Ray Tube.
How is a cathode ray tube used to convert an electrical signal into a visual signal?
What are ‘Becquerel rays’?
From α, β and γ-rays, name the one which is not affected by electric or magnetic field?
State one use of radio-isotopes.
Which of the following statements is/are correct?
- α particles are photons
- Penetrating power of γ radiation is very low
- Ionization power is maximum for α rays
- Penetrating power of γ radiation is very high
Heavy radioactive elements eventually turn into ______.
The activity of a certain radionuclide decreases to 15 percent of its original value in 10 days. What is its half life?
[ln (0.15) = -1.9]
A radioactive element is placed in an evacuated chamber. Then the rate of radioactive decay will ______.
