1B24 Waves Optics and Acoustics Lecture 13 of 33 (UCL)

Page 1

"! # $ %& &' ( *) %,+- . / 1032 45 *67 8'$ 9 # $ %:

%;%& 9 <'= >'& ?@ A % B>C-DFEHGJI E-K EMLONJP Q:LOGRQ:CSNJCTDOUVGRKWUXK#CYNJC[Z \^]`_*aSb cSdfeOg@] _ihT] dj]`bjaSkl_ mAhSnpoqh mr] cSdfe-sTaSo9]`s tMu vwbjkxnpyzh{_jkxu|h[v@}Ts-~ m v g-nx}Sy v@dfyza-~ ]9}{_8 Vezd8_ihT]<]`}S]9dfy@u cSdfezc[v@yzv _inxez} np} v"y{v@b` 8hT] djv _i] e@ ]9}T]9djy u _idiv }Sbf V]`d nxb _ihS] djv _i] v _*mAhSnxoqh7v@} ]9kx] ]9}{_ e y{v@b v _ sSe-]`b mrezdj ez} vw}T]9npy@h tRezaSdfnp}Syw]9kp] ]`}{_ 8hS] cSdf]9bfbjaSdf] npb * [ S v@}Ts ^v@b*_jhS] djv _i]"v _ mAhSnpoqh7vw Ve@djo9] sSe-]`b m e@ dj npb*_jhS] cSdfe-sSaTo`_ e@ _jhS] Vezdfo9]"v@}Ts _jhS] div _i] e eFgz] ]`}{_ np}H_jhS] sSnxdj]`o`_inxez}He $_ihS] Ve@djo9] _ihTnpb*sTe-]`b*m e@dj v _ v>djv _i] S { @ S c ]`d8aS}Snl_ v@dj]9vT [ezd _ihT]<djv _i] e ;]`}S]9dfy@u _idjv@}Sbf V]`dAc ]`d aT}Snx_ v@df] v"npb ¡£¢V ¤ f¥ * * S [ S ¦ * @¨O§ ©Mª « ¬®­ § ¢ ª © ¥ ¤ v@}Ts v g@]9div yznp}Sy eFgz]`d v¯cR]9djnxe-s>mr]< h[v Sgz ] ° ²± ¡ ³ µ¶´ * ©Mª z¨§ ·¶ ´ ¸ ¨ ª §f @¨F§ ¹ µ¶´ ª §qº z¨§ ¤ _ihS] np}{_j]9}Sbfnx_»uz SmAhTnpoqh npb8]½¼Tv@o½_iklu ¹ ±X¾ ³` ¿ EMC[Z À LOE-ÁYE-KRDwGJI  GRÀ:K à 8hS]"kxezaSsS}T]9bjb e@ rv>bfezaS}Ss npb aTbja[v@kxkxu ]9v@bjaTdj]9s7ez}7v kxezy{v@dfnx_ih nxo<bfo v@kx] ~Ayznlgz]`} _jhS] }Ma tR]9dre@ c eFmr]9dfb8e@ ´FÄ eFgz]`d mAhSnpoqh>_jhS]*cTdj]9bfbjaSdf]<v cTkpnx_jaSsS] ¢ÅcTdjezcRezdf_jnpez}Sv@k _jew_ihS] bjÆMa[v@df]"dje e@_*e $_ihS] cReFm ]`d ¥ g v@dfnp]9b` _jhSnpb npb*aT}SsS]9dfbf_iv@}Ss[v@tTkp]@ ÇÈbf_qv }Ss[v@dfs e@ np}{_j]9}Sbfnx_»u nxb8bj]9kx]9o½_i]9s É ° ¨ ´FÄ Ê[Ë §AÌ Ê § mAhSnxoqhÍnxb v@tRezaT_$_ihT]8kpn nx_ e@ v@aSsSnxtSnpkxnx_»u Vezd v hMa v@} & 8hS]8_»u cSnxo v@k[kx]`gz]`k[e@ v o`ez}-~ g@]9djbjv _inxez} t ]½_»m ]`]9} _»mrewcR]9e@cSkp] bÎ_qv@}SsTnp}Sy¯o9kxezbj] _jezyz]½_ihS]`d nxbAv@tRezaT_ ´FÄ Ì § Ð _ihT]9dAnp}{_i]`}Sbjnl_inx]9bAv@df] ]9v@bjaSdf]9s [df]9kpv _inlgz] _ie"_jhS] bf_qv }Ss[v@dfs nx}M_j]9}Sbfnx_»u@ [Ê npÏ }|t ]`kpb` Ê Ñ J° ° ¨ ´FÄ@Ò _ihS]`} ° npb:biv nps _je*tR] Ó$tR]9kpb:kpe@aSsS]9d _ihSv@} ° ¨ @ezd:kpezy ¨ ¢Å° ° ¨ ¥ ÓF 8hS]"tR]9kX vÍ Åv@o½_iezd*e@ npb ÆMaSnl_i]"vwo`e{v@dfbj] ] v@bfaSdj] bje>_jhS] sS]`Ë o9nptR]9k ¢ÅsSt ¥ npb e zdj] Vdf]9ÆMaS]`}M_jkxu@ Ç sS]`o9nxt ´F]`Ä k® Se@ o9e@aSdjbf]@ Jnpb8ez}T] _i ]9}{_jhHe@ ;v"t ]`k® ´ Ô ~ ´


Õ e@djdj]`bjcRez}SsSnx}Syzkluz Mez}S]AsS]`o9nptR]9k:¢VsSt ¥ npb v Åv@o½_iezd e@ ´FÄ ¨jÖ ´zØÙÔ z_ihSdf]9] sS]9o`nptR]9kxb Ë$× ¢ Ô sSt ¥ npb ´ Ä ¨jÖ Ú ¶ × 8hS]r] v@d:h[v@b v@} nx}{_i]9}Tbjnx_»u djv@}Syz] Vdfe #Û aSbÎ_;hS]9v@djnx}SyA_ie*cSv@np} e@ Sv@t e@aT_ ´ ¶ tR]9kxb9 Ç Sound }Ma tR]9dAe@ ;]½¼Tv levels cSkp]`bAv@dj] bfhSeFmA}Hnp}>ÜSyzaSdj] ´FÔ ´ db 220 200

Underwater sonar

Rocket launcher

180 Threshold of pain

Shot 160 Jet engine at 30 metres

140 120

Rock concert 100 Shout

80

Conversation

60

Birds Bats

40

Whispering Threshold of Hearing

20 0

1

10 100 Frequency Hz

1000

10000

100000

;Ý npy@aSdj] ´FÔ ´ É Þ;¼Tv cSkp]`bAe@ ;bfezaS}Ss np}{_j]9}Sbfnx_inx]9b` ß e _i] _ihSv _ v@b mr]9kxk&v@b yznlg np}Sy v } np}{_i]`}Sbjnl_»uH_ie|v>bÎ_qv@}Ts[v@djs _ihS]"sS]`o9nxt ]`k&bjo9v@kp] o9v@}¯t ] aTbj]9s¯_iewàqá â*ãTä@åiæ _»mre bjnpy@}[v@kpb`É e@}S] bjnxyz}[v@k-e@ Rnp}{_i]`}Sbjnl_»u ° nxb ­ sSt¯bÎ_idje@}Syz]9d _jh[v@} v@}Se@_jhS]9dAe@ np}{_j]9}Sbfnx_»u ° nl § Ë ­ ´ Ä kxezy ¨Aç °° § è Ø Ë Ë éëê;ì8ífê î8ïrðfñ ò óõô öT÷Jðfñ ø ô¦ùûúYü ýrþ ÿ ü ý Ìv@df]> ] gz]`]<g nxkpsSe ]9ez}S @o`]`] sH Vv ez_8d m m v vFgzg@]`]9b*b ezt } ]`npv }Sy Ü[}Sdfnl] _i [] ]`bfo`_j_jdj]9nps#}TySv [_"v@}S] v s oqh#bj]`]9]`} }Ss _ihS ]< 8}ShTez] d ]9}Sv@s3k e@e AsS_i]`hTb9] SmAbf_ihSdfnpnx}Soqh y ´ Ô ~ ¶

soundsdb.mcd

1

08/02/99 14:25


nxb Û aSbÎ_ v@} ] ¼Tv cTkp]@ v@kxt ]`nx_ v@} ] ¼-_jdj] ] e@}S]@ e@ vwsSnxbjo`ez}{_inp}MaSnl_»u np} _jhS] bÎ_idfnp}Sy v@}Te@_ihS]`d&m v u e@ _jhSnp}T nx}Sy e@ J_jhS]Adjnpy@nps bfaScScRezdf_ nxb v@b$v@}¯nx}TÜ[}Snl_i]9klu v@bfbjnlgz]8bf_jdjnx}SyS \^]`_ Ùb }SeFm v bj 7mAh[v _"h[v cSc ]`}Sb mAhS]`}1m ] eznx}Y_»mre sSnpbfbjn nxk v@d bÎ_idjnx}Syzb<_iezyz]½_ihS]`d9 Ñ»}{_iaTnx_inlgz]`kxu mr]Ío9v@} bj]9] _ih[v _ nl rmr]¯_inp]¯v Û ezdj] v@bjbfnxgz]¯ bÎ_idjnx}Sy ez} _jhS]¯]9}SsYe@ 8v kxnpyzh{_ ez}S] -nl _ bryze@np}Sy _ie tR] h[v@djsÍ Vezd _jhS]*kxnpyzh{_ bf_jdjnx}Sy _je bjhSv@ @] nl_ h[v@djsw]9}SezaTyzhw_ie yz]½_ v@kpk _ihS] ]9}T]9djy u np}{_ie¯nl_ Ì ] m v@}{_A_ie¯ÆMa[v@}{_inl u>_ihTnpb8 ] ]9o½_ Ñ v@yznp}T] ezaSd bÎ_idfnp}SyS TaS}SsS]`d _i]9}Tbjnpe@ } < SdfaS}S}Snx}Sy Vdje np}MaSb nx}TÜ[}Snl_»uÍ_je cTkpaSb nx}TÜ[}Snl_»uz AtSaT_ mAnl_ihë_ihT] bj]`o`_inxez}W Vdje np}MaSb>nx}TÜ[}Snl_»u _je h[v g np}Sy sS]`}Sbjnl_»u _jh[v _" Vdje Ä _ie7nx}TÜ[}Snl_»u h[v g np}Ty sT]9 }Sbfnx_» u ¸ 1 8hT]|_j]9}Sbfnpez}3Ä nxb _ihS]|bjv ] nx}1_i¸ hSË ] _»mre¯h[v@kxg@]9b` [tSaT_8_ihT]<sTn ]9dj]`}So9] nx} sS]9}Tbjnx_»u § ]9v@}Sb _ihSv _8_ihS] m v gz]<bjcR]9]`sSb mAnxkpkRt ] sS n ]`dj]`}M_9 hSv _ aSbÎ_¯h[v@cScR]9}#v _"_ihT] t ezaT}Ss[v@dÎ u Õ kp]9v@djkluY_jhS] sSnpbfcSk v o9] ]9}{_¯e@ A_jhS] bf_idfnp}SÌ y aSbf_ tR] o`ez}{_inp}MaSe@aS b e@_jhS]9dÎmAnpbj] nx _ b*tTdjez ]9} Ç*kpbfew_ihT] _idjv@}Sbfg@]9dfbj]¯ Vezdjo`] n aSv@bfk _A]`tRkp] ] o9]9e@}{}M_A_jnpe@}M aSezbf_jaTdj b nx}S wyS [e@_jv@hS}T]9s dÎmAmrnp]<bf] mAm nxkp] k tSh[djv ]9gzv@]< >v nx_9Ü[ }Snl_i] Vezdfo9] v@o½_inx}Sy"ez} v@}|np}TÜS}Snx_j]9bÎ~ Ì ]<bf]9}SsHv m v gz] np}> Vdfe , np}MaSb8np}-Ü[}Snx_»uRÉ$kx]`_Anx_ h[v gz]<aS}Snx_ v cSkxnx_jaSsS] ¢V ¤ f¥ Ê !#" Ø Ì ] ]½¼-c ]`o`_ bje ] e@ :_ihS] m v gz] _je¯t ] _idjv@}Sb nl_j_i]`s np}{_ie"_jhS] bj]9o`ez}Ss h[v@kx $ ¢ ¤ f¥ & %' ( Ê *)+#" ¤ v@}Ts bfe ] _je¯t ] dj#] []9o½_i]`s , ¢ ¤ f¥ . -/ ( 0 #" Ø ß e@_i]*_jh[v _8_jhS]9df] npb }Se"}T]9y{v _jnxg@]½~»y@eznp}Sy m v gz] nx}>_ihS] bf]9o9e@}Ss|h[v@kx ^~$v@}{u _jhSnp}Ty¯_jh[v _ yz]½_ib nx}{_ieÍ_jh[v _*h[v@kx &sSnpbjv@cScR] v@dfb*_ieFm v@djsSb*np}TÜ[}Tnx_»uz ] v@dj] aSbjnx}Sy>sS n ]`dj]9}{_ _»u-cR]½~ Åv@o`]9b8_ie¯sSnxbf_jnp}SyzaTnpbjh _jhS] _idiv }Sb nx_f_i]9s|v cSkxnx_jaSsS] % Ì Vdfe _jhS] _in ] Ð aSd8_»m e o9e@}M_jnp}MaSnl_»u o9ez}TsSnx_jnpez}Sb yznxg@] ¢ Ä ¤ f¥21 , ¢ Ä ¤ f¥ ¢ Ä ¤ f¥21 , ¢ Ä ¤ f¥65

$ ¢ Ä

¤ f¥

7$ ¢ Ä ¤ f¥ Ø 8 aTtSbf_jnx_ia-_inp}TyS [v@}Ss _iv@ Mnp}Sy¯ezaT_A_jhS] o9e e@}> Åv@o`_jezd8e@ 9 Sm ] h[v gz] - % 1 ´ © 1 © - © % § Ë Ë ´ Ô ~ Ô 43

¢Å Å¢

´FÔ ¶´ ¥ ´FÔ ¥


Vdfe mAhSnxoqh mr] h[v gz]@ "bfaStSbÎ_inx_jaT_inx}SyW Vezd % Vdfe `] Æ aSv _inxez} ´FÔ ´ nx}M_jeW]9ÆMa[v ~ _jnpez} ´FÔ ¶ © 1 © - 1 © 1 © - Ä § § - © © Ë Ë © Ë 1 © § : a-_ v@kpk{_jhS] © b&v@df] e@ J_ihT] Vezd ª ¹ ª {v@}Ss ª Ë nxb _jhS] § biv ] _jhSdje@aSyzhSeza-_ º Ë bfe ¢Å ´ Ô Ô ¥ -" º Ë º § º Ë 1#º § v@}Ss nx_ VezkpkxeOmAb _jh[v _ ¶º ¢Å ´ Ô ; ¥ % Ë Ø ºË1 º§ ß e _i] _ih[v _ _ihT] df] []`o`_inxez} v }Ss _jdiv@}Sb nxbjbfnpez}|o9e ] < o`np]9}{_jb v@df] nx}SsS]9cR]9}TsS]9}{_ e Vdf]9ÆMaS]9}To`uz r_ih[v _ nxb9 np}SsS]`c ]`}SsS]`}M_Íe@ m v g@]9kp]`}Sy@_jh 8hSnxb¯npb _ie tR] ] ¼-c ]`o`_i]`s 8v@b _jhS]9df] nxb$}Se oqh[v div@o½_i]9dfnpbÎ_inpoAkx]9}Sy@_jh¯np}¯_ihS] cSdje@tSkp] ¢V_»mre bf] nl~ np}TÜ[}Tnx_i] bf_idfnp}Sy@b ¥ Mbfe _jhS]9df]<nxb8}Se dj] v bjez}|_ie¯]½¼-cR]9o½_ v"sS]`c ]`}SsS]9}To9] e@} m v gz]9kx]9}Sy _ih

=?>A@CB DFE @HG IJ@LKNMPO Q2R MTS MPOFUVRXW MPUVRZY\[

´ Ô ?~ ;


Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.