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.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
An electron accelerated by 1 kV travels 5 km towards conducting plate of infinite extension is moving in the direction perpendicular to the plate. Calculate the minimum surface charge density on the conducting plate so that the electron cannot collide with the plate.
Write Kirchhoff's rules for electric circuit.
Define electric field intensity and equipotential surface in current carrying conductor.
A Young's double slit apparatus has slits separated by $0.28\ mm$ and a screen $48\ cm$ away from the slits. The whole apparatus is immersed in water and the slits are illuminated by the red light $(\lambda=700\ \text{nm}$ in vacuum$)$. Find the fringe$-$width of the pattern formed on the screen.
→A curve is represented by $\text{y}=\sin\text{x}.$ If x is changed from $\frac{\pi}{3}$ to $\frac{\pi}{3}+\frac{\pi}{100},$ find approximately the change in y.
→$A$ small block $B$ is placed on another block $A$ of mass $5\ kg$ and length $20\ cm.$ Initially the block $B$ is near the right end of block $A. A$ constant horizontal force of $10N$ is applied to the block $A$. All the surfaces are assumed frictionless. Find the time elapsed before the block $B$ separates from $A.$
→What is the power dissipated by an ideal inductor in ac circuit? Explain.
Write down the phenomena seen or observed during the generation of static electricity.
Depict the field-line pattern due to a bar magnet.
The density of water at $4^\circ C$ is supposed to be $1000\ kg m^3.$ Is it same at sea level and at high altitude?
→