The energy spectrum of $\beta$-particles [number $\mathrm{N}(\mathrm{E})$ as a function of $\beta$-energy E] emitted from a radioactive source is

JEE Main · 2006 · 30 Apr 2006 · Offline · Modern Physics

The energy spectrum of

β

-particles [number

N (E)

as a function of

β

-energy E] emitted from a radioactive source is

(A)(see structure)
(B)(see structure)
(C)(see structure)
(D)(see structure)
✓ Correct

Answer: (D)

Solution

Beta decay shares the released energy between the emitted electron and an (anti)neutrino, so the electrons come out with a continuous range of energies rather than a single sharp value. The number

N (E)

rises from zero, passes through a maximum at a fairly low energy, and then falls back to zero at the end-point energy

E_{0}

, which is reached only when the neutrino carries off almost nothing. The spectrum is therefore the smooth continuous curve that terminates at

E_{0}

JEE Main · 2006 · 30 Apr 2006 · Offline · Single correct option

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