6.201. AE = 2:1 2 h 2 /mV (3n 2 n) 1 / 3 = 2.10-22 eV.
6.202. (a) dn, (m 3 1a^2 h^3 ) v^2 dv; (b) (v)/vmax = 3/4.
6.203. dnk = 8nk-4 d?.
6.204. p = 2 /3n (T) = rai-th 2 /5m) n 5 / 3 5.10 4 atm.
6.205. A = kT (iT/A T — 2) = 4.5 eV.6.206. n 1/1 Uo /T = 1.02, where U (^0) = T max + A, T max --=
(3a 2 n)2/3 h^2 /2m. A is the work function.
6.207. Emzn=
r2kT1r2 In
11= 0.33 eV.
6.208. cx =^1 op^ ach^
aT kT x,
— = —0.05 K-1,
AE 0 is the forbidden band width.
In
6.209. AE — 2k
(T-1)
= 1.2 and 0.06 eV.
6.210. T = t/ln (9—P1) P2 -= 0.01 S.
( 3— P2) Pi
6.211. n = hB V I elp V H = 5.10 15 cm-3, u 0 = 1 VH/hB =
= 0.05 m 2 /(V • s).
6.212. I uo — u:1 = 1/1B = 0.20 m 2 /(V•s).
6.213. n:/n- = = 4.0.
6.214. (a) P = 1 — exp (—kt); (b) T = 1/k.
6.215. About 1/4.
6.216. 1.2 10 15.
6.217. r X16 s.
6.218. 1' = 5.3 days.
6.219. 4.6.10 2 part./min.
6.220. k = —(1/t) In (1 — ri) ri/t = 1.1.10-5 s-1, T = 1/A =
= 1.0 years.
6.221. T = 4.5-10 9 years, A = 1.2-10 4 dis./s.
6.222. 4.1 • 10 3 years.
6.223. About 2.0-10 9 years.
6.224. 3.2.10 17 and 0.8-10 5 dis/(s • g) respectively.
6.225. V = (A/A') exp (—t In 2/T) = 6 1.
6.226. 0.19%.
6.227. T (^1) -= 1.6 hours, T2 = 9.8 hours; N 2 /N 1 = (T 2 /T 1 ) x
X exp (ln A 2 — In A 1 ) = 10.
6.228. t = —(T/In 2) In (1 — AI q) = 9.5 days.
6.229. (a) N2 (t) = No x2 ki (^) e-k2t);
(b) trn = inxi(k±/xX22)
6.230. (a) N2 (t) = XATiot exp (—kt); (b) tm = 1/k.
x_e-A 1 t
6.231. N3 (t) = ( 1 + ,
2 —"1 ) •
6.232. "VD = N0?1 exp (—kit) = 0.72.10 11 part./s, N a
No — e-2v2 (^1) )? 1? /(?1 (^2) — = 1.46.10 11 part./s. (^) Here No
is the initial number of Bin° nuclei.
6.233. (a) Pb 2 "; (b) eight alpha decays and six beta decays.
where p eAE0/2hTt