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The decay constant of a radio isotope is λ. If A₁ and A₂ are its activities at time t₁ and t₂ respectively, the number of nuclei which have decayed during the time (t₁ – t₂):
Options
(a) λ (A₁ – A₂)
(b) A₁t₁ -A₂t₂
(c) A₁ – A₂
(d) (A₁ – A₂) / λ
Correct Answer:
(A₁ – A₂) / λ
Explanation:
Activity is given by A = dN/ dt = -λN
Activity at time t₁ is A₁ = – λN₁
and activity at time t₂ is A₂ = -1 N₂ as t₁ > t₂ therefore, number of atoms remained after time t₁ is less than that remained after time t₂.
That is, N₁ < N₂. number of nuclei decayed in (t₁ - t₂)
= N₂ - N₁ = (A₁ - A₂) / λ
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Topics: Atoms and Nuclei
(136)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- In an ac circuit an alternating voltage e = 200 √2 sin 100 t volts is connected
- Pure Si at 500 K has equal number of electron (nₑ) and hole (nₕ) concentrations
- P-type semiconductors are made by adding impurity element
- A ball is projected upwards from the foot of a tower. The ball crosses the top
- A Zenor diode has a contact potential of 1 V in the absence of biasing. It undergoes
Topics: Atoms and Nuclei (136)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
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