Question
Give a brief explanation about Radioactivity.
✓
Answer
→Becquerel discovered radioactivity in 1896 purely by accident.
→While studying the fluorescence and phosphorescence of compounds irradiated with visible light, Becquerel observed a phenomenon.
→After illuminating some pieces of uranium - potassium sulphate with visible light, he wrapped them in black paper and separated the package from a photographic plate by a piece of silver. When, after several hours of exposure, the photographic plate was developed.
→By doing this, blackness appeared on the photographic plate.
→This blackness must be due to some radiation emitted from the compound.
→Experiments performed subsequently showed that radio activity was a nuclear phenomenon in which an unstable nucleus undergoes a decay. This is referred to as radioactive decay.
→Three types of radioactive decay occur in nature.
(i) $\alpha$-decay in which a helium nucleus ${ }_2 He ^4$ ( $\alpha$-particles) is emitted.
(ii) $\beta$-decay in which electrons or positrons are emitted.
(Positron : particles with the same mass as electron, but with a charge exactly opposite to that of electron.)
(iii) $\gamma$-decay in which high energy (hundreds of $k e V$ or more) photons are emitted.
→While studying the fluorescence and phosphorescence of compounds irradiated with visible light, Becquerel observed a phenomenon.
→After illuminating some pieces of uranium - potassium sulphate with visible light, he wrapped them in black paper and separated the package from a photographic plate by a piece of silver. When, after several hours of exposure, the photographic plate was developed.
→By doing this, blackness appeared on the photographic plate.
→This blackness must be due to some radiation emitted from the compound.
→Experiments performed subsequently showed that radio activity was a nuclear phenomenon in which an unstable nucleus undergoes a decay. This is referred to as radioactive decay.
→Three types of radioactive decay occur in nature.
(i) $\alpha$-decay in which a helium nucleus ${ }_2 He ^4$ ( $\alpha$-particles) is emitted.
(ii) $\beta$-decay in which electrons or positrons are emitted.
(Positron : particles with the same mass as electron, but with a charge exactly opposite to that of electron.)
(iii) $\gamma$-decay in which high energy (hundreds of $k e V$ or more) photons are emitted.
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