1. Define ‘activity’ of a radioactive substance. 2. Two different… - Vidyadip

Question

Define ‘activity’ of a radioactive substance.
Two different radioactive elements with half lives T₁ and T₂ have N₁ and N₂ undecayed atoms respectively present at a given instant. Derive an expression for the ratio of their activities at this instant in terms of N₁ and N₂.

✓

Answer

Number of radioactive nuclei decaying per second at any time.
$R_1=\lambda_1N_1=\frac{0.693}{T_1}N_1$

$R_2=\lambda_2N_2=\frac{0.693}{T_2}N_2$

$\frac{R_1}{R_2}=\frac{N_1}{N_2}\times\frac{T_2}{T_1}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Nuclei→Nuclei — all question types→Physics STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

Consider a 10cm long piece of a wire which carries a current of 10A. Find the magnitude of the magnetic field due to the piece at a point which makes an equilateral triangle with the ends of the piece.

The radius of gyration of a uniform disc about a line perpendicular to the disc equals its radius. Find the distance of the line from the centre.

A violin player riding on a slow train plays a 440Hz note. Another violin player standing near the track plays the same note. When the two are close by and the train approaches the person on the ground, he hears 4.0 beats per second. The speed of sound in air = 340m/s.

Calculate the speed of the train.
What beat frequency is heard by the player in the train?

Consider the charges q, q, and –q placed at the vertices of an equilateral triangle, as shown in Fig. 1.7. What is the force on each charge?

An $\alpha$-particle collides with nucleus after passing through the potential V volt. Prove that distance of closest approach of particle of atomic number $Z$ to the nucleus will be $14.4( Z / V ) \ Å$.
(Given that : $1 / 4 \pi \varepsilon_0=9.0 \times 10^9$ Newton-meter $^2 /$ Coulomb $^2$ and $e=1.6 \times 10^{-19}$ Coulomb)

A parallel plate capacitor with air between the plates has a capacitance of 8 pF (1pF = 10^–12F). What will be the capacitance if the distance between the plates is reduced by half, and the space between them is filled with a substance of dielectric constant 6?

Consider the situation shown in figure. What are the signs of q₁ and q₂? If the lines are drawn in proportion to the charge, what is the ratio $\frac{\text{q}_1}{\text{q}_2}?$

The numerical value of ionization energy in eV equals the ionization potential in volts. Does the equality hold if these quantities are measured in some other units?

The ground state energy of hydrogen atom is – 13.6 eV. If an electron makes a transition from an energy level – 0.85 eV to – 3.4 eV, calculate the wavelength of the spectral line emitted.To which series of hydrogen spectrum does this wave length belong?

A horizontal overhead power line carries a current of 90 A in east to west direction. What is the magnitude and direction of the magnetic field due to the current 1.5 m below the line?