... Gii: Ta cú n1 = N1 = N0 (1- e-t1 ) n2 = N2 = N1 (1- e-t2 ) = N0e-t1 (1- e-2t1 ) n1 /n2 = (1- e-t1 )/e-t1 (1- e-2t1 ) = (1- X)/X (1- X2) = 1/ X (1+ X) Vi X = e-t1 ú ta cú phng trỡnh: X2 + X = n2/n1 =9/64 hay ... ba cú 10 0 x (1, 6)2 ht nhõn 235U ; phn ng th 10 0 cú 10 0x (1, 6)99 Tng s ht nhõn b phõn ró n phn ng th 10 1 10 0 (1, 6 .10 1 1) 10 0 N = 10 0( 1, 6 + 1, 6 + 1, 6 + +1, 6 ) = = 6,88 .10 22 ht ỏp ỏn C 1, 6 Cõu ... th phỏt l: hc 15 = E4 E1 = -13 ,6.( - 1) eV = 13 ,6 ,1, 6 .10 -19 = 20,4 10 -19 (J) 16 n hc 6,625 .10 34 3 .10 -> = = = 0,974 .10 -7m = 9,74 .10 -8m Chn ỏp ỏn B E E1 20,4 .10 19 14 Cõu 17 : Bn ht nhõn...