Give different units of radioactivity and define them.

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13.Nuclei

medium

Give the different units of radioactivity and define them.

Option A

Option B

Option C

Option D

Solution

The SI unit for activity is Becquerel $(\mathrm{B} q)$ named after the discoverer of radioactivity,

Henry Becquerel.

$(i)$ Activity of a substance having 1 disintegration per second is called 1 Becquerel (B $q$ ). $\therefore 1 \mathrm{~B} q=1$ decay/s

$(ii)$ Curie unit : The activity of a substance in which $3.7 \times 10^{10}$ disintegration per second take place is called l curie $(\mathrm{C} i)$.

$\therefore 1 \mathrm{Ci}=3.7 \times 10^{10}$ decay/s

In practice its smaller units are used,

$1 \mathrm{mC} i=3.7 \times 10^{7}$ decay/s $=10^{-3} \mathrm{Ci}$

$1 \mu \mathrm{C} i=3.7 \times 10^{4}$ decay/s $=10^{-6} \mathrm{C} i$

Curie unit is the old experimental unit.

(iii) Rutherford unit : It is defined as the activity of a quantity of radioactive substance in which $10^{6}$ (ten lakh) nuclei decay per second is called Rutherford $(\mathrm{rd})$. $\therefore 1 \mathrm{rd}=10^{6}$ decay/s

Standard 12

Physics

A radioactive material of half-life $T$ was produced in a nuclear reactor at different instants, the quantity produced second time was twice of that produced first time. If now their present activities are $A_1$ and $A_2$ respectively then their age difference equals :

normal

For a substance the average life for $\alpha $ -emission is $1620\ years$ and for $\beta $ emission is $405\ years$ . After how much time the $\frac {1}{4}$ of the material remains by simultaneous emission ………… $years$

hard

A certain radioactive nuclide of mass number $m_x$ disintegrates, with the emission of an electron and $\gamma$ radiation only, to give second nuclied of mass number $m_y.$ Which one of the following equation correctly relates $m_x$ and $m_y$ ?

medium

A radioactive sample with a half life of $1$ month has the label : “Activity$=2\, micro\,\,curies$ on $1-8-1991$.'' What will be its activity two months earlier ………… $micro\,\, curies$.

medium

(AIPMT-1988)

The half-life of ${ }^{198} {Au}$ is $3 \,days.$ If atomic weight of ${ }^{198} {Au}$ is $198\, {g} / {mol}$ then the activity of $2 \,{mg}$ of ${ }^{198} {Au}$ is ….. $\times 10^{12}\,disintegration/second$

hard

(JEE MAIN-2021)

Give the different units of radioactivity and define them.

Solution

Similar Questions

A radioactive material of half-life $T$ was produced in a nuclear reactor at different instants, the quantity produced second time was twice of that produced first time. If now their present activities are $A_1$ and $A_2$ respectively then their age difference equals :

For a substance the average life for $\alpha $ -emission is $1620\ years$ and for $\beta $ emission is $405\ years$ . After how much time the $\frac {1}{4}$ of the material remains by simultaneous emission ………… $years$

A certain radioactive nuclide of mass number $m_x$ disintegrates, with the emission of an electron and $\gamma$ radiation only, to give second nuclied of mass number $m_y.$ Which one of the following equation correctly relates $m_x$ and $m_y$ ?

A radioactive sample with a half life of $1$ month has the label : “Activity$=2\, micro\,\,curies$ on $1-8-1991$.'' What will be its activity two months earlier ………… $micro\,\, curies$.

The half-life of ${ }^{198} {Au}$ is $3 \,days.$ If atomic weight of ${ }^{198} {Au}$ is $198\, {g} / {mol}$ then the activity of $2 \,{mg}$ of ${ }^{198} {Au}$ is ….. $\times 10^{12}\,disintegration/second$

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