Q. In a thermo nuclear reaction 10-3 Kg of hydrogen is converted into 0.99 × 10-3 kg of helium. If the efficiency of the generator is 50%, the electrical energy generated in KWH is
(a) 105
(b) 1.5 × 105
(c) 1.25 × 105
(d) 1.3 × 105
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Ans: (c)
Sol: Sol: 2×1H2 →2He4
Mass defect , Δm = 10-3 −0.99×10-3
= 0.01×10-3kg = 10-5 kg
Energy, E = Δmc2
E = 10-5 ×(3×108)2
= 9×1011 J
Efficiency , η = 50% = 50/100 = 1/2
Electrical Energy , = (1/2)× 9×1011 = 4.5×1011J
1KWH = 3.6×106 J
Hence , E = 4.5×1011/3.6×106
E = 1.25×105KWH