Page 84 - 標檢局雙月刊198期

倚䧙 L A = n Np 㗪(n 䁢ᶨᾳ㔠)炻堐䣢㬋 ⣰➡ Np ⻎ᾉ嘇䘬㋗ⷭ A 2 ⍲ A 1 䘬冒䃞⮵㔠㭼 n = ln(A 2/A 1) ˤ ln(A 2/A 1) =1 Np 㗪炻 A 2/A 1 = e (e 䁢 Euler's number炻 䫱㕤 2.7182818) ˤ L A ⎗䧙 䁢冒䃞⮵㔠㋗ⷭ 居䇦 B 㭼炻ㆾ冒䃞⮵㔠㋗ⷭ䳂ⶖˤ 倚䧙 L X = m dB = (m/10) B (m 䁢ᶨᾳ㔠) ⮵㔠㭼䌯慷 㗪炻堐䣢ẍ X 䁢⛯㕡ᾉ嘇ㆾỤ≇䌯䘬 慷炻lg(X/X 0) = m/10ˤ⚈㬌炻䔞 L X = 1 B炻⇯ X/X 0 = 10炻䔞 L X = 1 dB炻⇯ X/ ↮居 dB X 0 = 10 1/10 ˤL X 䁢ẍ X 0 䁢⍫侫➢㸾ᷳ≇ 䌯ỵ㸾ˤ 1 B = 10 dB = (ln10)/2 Np = 1.151 293 Np 1 dB = 0.1 B = 0.115 129 3 Np 堐 9 冯 CGS ╖ỵ⇞⍲ CGS-檀㕗╖ỵ⇞䚠斄ᷳ朆 SI ╖ỵ 慷⎵ ╖ỵ⎵䧙 ╖ỵ䫎嘇 ὅ SI ╖ỵᷳῤ í7 傥慷 䇦㟤 erg 1 erg = 10 J í5 ≃ 忼⚈ dyn 1 dyn = 10 N í2 ≽≃湷⹎ 㱲 P 1 P = 1 dyn s cm = 0.1 Pa s 2 í1 í4 í1 2 忳≽湷⹎ ⎚㈀⃳ St 1 St = 1 cm s = 10 m s 4 í2 í2 Ṗ⹎ 䅁㍸ sb 1 sb = 1 cd cm = 10 cd m í2 4 䄏⹎ 廣德 ph 1 ph = 1 cd sr cm = 10 lx í2 í2 í2 ≈忇⹎ ụ Gal 1 Gal = 1 cm s = 10 m s í8 2 䡩忂慷 楔⃳⢓⦩ Mx 1 Mx = 1 G cm = 10 Wb í4 í2 䡩⟜⭮⹎ 檀㕗(gauss) G 1 G = 1 Mx cm = 10 T 3 í1 䡩⟜⻟⹎ ⤏㕗䈡(oersted) Oe 1 Oe ؙ (10 /4ʌ) A m Τȃ๖ᇭ 妰慷╖ỵ㗗䣦㚫䘤⯽䘬䓊䈑炻⬫⮯晐叿䥹⬠䥹㈨䘬忚㬍侴ᶵ㕟䘤⯽␴㓡忚ˤ SI 冯㖑⃰冒䘤⿏䘬╖ỵ⇞ᶵ⎴炻⬫㗗⺢䩳⛐♜⭮䘬䥹⬠➢䢶ᶲ䘬ᶨᾳ⬴㔜橼䲣炻 ℟㚱䴙ᶨ⿏␴⚳晃⿏ˤSI ᶵ㗗⚢⭂ᶵ嬲䘬炻侴㗗䁢㺧嵛ℐ䎫⮵慷㷔崲Ἦ崲檀䘬天 㯪侴ᶵ㕟䘤⯽炻䚖⇵ṵ㚱姙⣂㚱斄 SI 枸㛇䘬ᾖ妪ⶍἄ㬋⛐忚埴ˤᶵ忶⌛ἧṲ⼴ 78! Bureau of Standards, Metrology and Inspection!