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The energy released by the fission of one uranium atom is 200 MeV. The number of fission per second required to produce 6.4 W power is ______.

Asked in GUJCET 2015 · Energy released in fission and fusion

• (1) 2×10¹¹
• (2) 10¹¹
• (3) 10¹⁰
• (4) 2×10¹⁰

Step-by-step solution

Why the other options are wrong

• (2) 10¹¹ follows from taking 400 MeV, i.e. 6.4×10⁻¹¹ J, for one fission instead of 200 MeV: 6.4/(6.4×10⁻¹¹)=10¹¹.
• (3) 10¹⁰ needs both slips together — 400 MeV per fission and an exponent one too high, 6.4×10⁻¹⁰ J.
• (4) 2×10¹⁰ comes from writing 200 MeV as 3.2×10⁻¹⁰ J; it is 3.2×10⁻¹¹ J.

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