Question

Two deuterons each of mass m fuse to form helium resulting in release of energy E the mass of helium formed is

(A) m + (E / C²)

(B) [E / (mC²)]

(C) 2m – (E / C²)

(D) 2m + (E / C²)

Answer 1

The correct option is (C) 2m – (E / C²).

Explanation:

E = (Δm)C² ....(1)

Δm = mass defect

If M is mass of helium formed then Δm = (m + m) – M

∴ Δm = 2m – M

∴ from (1), E = (2m – M)C²

∴ (E / C²) = 2m – M

∴ M = 2m – (E / C²)