MHT CET202615 April 2026Morning ShiftPhysicsNuclear PhysicsActual
Two different radioactive elements with half lives T₁ and T₂ have undecayed atoms N₁ and N₂ respectively, present at a given instant. The ratio of their activities at this instant is
Options
- AN₁ T₁ N₂ T₂
- BN₁ T₂ N₂ T₁
- CN₁ T₂ T₁ T₂
- DT₁ T₂ N₁ N₂
Correct answer
B. N₁ T₂ N₂ T₁
Step-by-step solution
Activity of a radioactive element is given by A = N The decay constant is related to half-life T as = 2 T For the first element, activity A₁ = 2 T₁ N₁ For the second element, activity A₂ = 2 T₂ N₂ The ratio of their activities is A₁ A₂ = 2 T₁ N₁ 2 T₂ N₂ = N₁ T₂ N₂ T₁ Answer: N₁ T₂ N₂ T₁