{"id":745,"date":"2016-08-01T09:50:31","date_gmt":"2016-08-01T07:50:31","guid":{"rendered":"http:\/\/www.zsvltava.cz\/fyzika\/?p=745"},"modified":"2025-03-19T19:49:11","modified_gmt":"2025-03-19T18:49:11","slug":"blesk","status":"publish","type":"post","link":"https:\/\/www.zsvltava.cz\/fyzika\/?p=745","title":{"rendered":"Hromy a blesky"},"content":{"rendered":"<p><strong>Blesk<\/strong> je sv\u011bteln\u00fd projev bou\u0159liv\u00e9 cesty elektricky nabit\u00fdch \u010d\u00e1stic do m\u00edsta, kter\u00e9 je opa\u010dn\u011b nabit\u00e9. P\u0159esto\u017ee trv\u00e1 jen velmi kr\u00e1tkou dobu, uvoln\u00ed obrovsk\u00e9 mno\u017estv\u00ed energie. Blesk si vyb\u00edr\u00e1 opa\u010dn\u00e9 m\u00edsto podle pravidel, kter\u00e1 n\u00e1m zat\u00edm nejsou \u00fapln\u011b zn\u00e1m\u00e1. <\/p>\n<p>Je zn\u00e1m\u00e1 \u0159ada p\u0159\u00edpad\u016f, kdy blesk ude\u0159il vedle domu, na kter\u00e9m byl bleskosvod. \u00daderem blesku u\u017e zahynul nejeden \u010dlov\u011bk. D\u016fvodem m\u016f\u017ee b\u00fdt fakt, \u017ee m\u00edstem, kde se nejv\u00edce hromad\u00ed n\u00e1boj jsou hroty. \u0160pi\u010dka jehly je tedy pro vyb\u00edjen\u00ed mnohem p\u0159ita\u017eliv\u011bj\u0161\u00ed ne\u017e nap\u0159\u00edklad siln\u00e1 ocelov\u00e1 ty\u010d.<\/p>\n<h3>Zaj\u00edmavosti o blesku<\/h3>\n<ul>\n<li>Nap\u011bt\u00ed mezi m\u00edsty mezi kter\u00fdmi blesk vznik\u00e1 bychom m\u011b\u0159ili \u0159\u00e1dov\u011b ve stovk\u00e1ch mili\u00f3n\u016f volt\u016f.<\/li>\n<li>Elektrick\u00fd proud by \u010d\u00edtal hodnoty v desetitis\u00edch Amp\u00e9r. <\/li>\n<li>Teplota uvnit\u0159 blesku m\u016f\u017ee dos\u00e1nout a\u017e 30 000 \u00b0C (Slunce m\u00e1 na povrchu teplotu 6 000 \u00b0C)<\/li>\n<li>Blesk je dlouh\u00fd n\u011bkolik kilometr\u016f.<\/li>\n<li>Blesk trv\u00e1 0,001 sekundy. To \u017ee ho vid\u00edme d\u00e9le je d\u00edky setrva\u010dnosti oka.<\/li>\n<li>Ka\u017ed\u00e9 2 sekundy ude\u0159\u00ed n\u011bkde na t\u00e9to plan\u011bt\u011b blesk. <\/li>\n<li>Ro\u010dn\u011b zas\u00e1hne blesk 24 000 lid\u00ed, 240 000 lid\u00ed zran\u00ed, obvykle doch\u00e1z\u00ed k pop\u00e1lenin\u00e1m.<\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.zsvltava.cz\/fyzika\/wp-content\/uploads\/2011\/06\/blesk.jpg\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.zsvltava.cz\/fyzika\/wp-content\/uploads\/2011\/06\/blesk.jpg\" alt=\"\" title=\"blesk\" width=\"429\" height=\"640\" class=\"size-full wp-image-746\" srcset=\"https:\/\/www.zsvltava.cz\/fyzika\/wp-content\/uploads\/2011\/06\/blesk.jpg 429w, https:\/\/www.zsvltava.cz\/fyzika\/wp-content\/uploads\/2011\/06\/blesk-201x300.jpg 201w, https:\/\/www.zsvltava.cz\/fyzika\/wp-content\/uploads\/2011\/06\/blesk-100x150.jpg 100w\" sizes=\"auto, (max-width: 429px) 100vw, 429px\" \/><\/a><\/p>\n<p><small>obr\u00e1zek zdroj: http:\/\/www.flickr.com\/photos\/7324617@N04\/4249181291\/<\/small> | <small><a href=\"http:\/\/www.flickr.com\/search\/?w=all&#038;q=lightning&#038;m=text\">dal\u0161\u00ed&#8230;<\/a><\/small><\/p>\n<h2>Blesky v cel\u00e9 sv\u00e9 kr\u00e1se<\/h2>\n<p><iframe loading=\"lazy\" width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/TaPgSWdcYtY\" frameborder=\"0\" allowfullscreen><\/iframe><\/p>\n<p><iframe loading=\"lazy\" width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/rVBn8R4qzYQ\" frameborder=\"0\" allowfullscreen><\/iframe><\/p>\n<h2>Hrom<\/h2>\n<p>Je zvuk, kter\u00fdm je blesk doprov\u00e1zen. Je d\u016fsledkem n\u00e1raz\u016f molekul vzduchu p\u0159i setk\u00e1n\u00ed s p\u00e1d\u00edc\u00edmi elektrony. Ty putuj\u00ed tak rychle a tak mocn\u011b \u017ee doslova rozr\u00e1\u017eej\u00ed okoln\u00ed \u010d\u00e1stice. D\u00edky tomu se uvol\u0148uje velk\u00e9 mno\u017estv\u00ed tepla. Jeliko\u017e je zvuk pomalej\u0161\u00ed, tak v p\u0159\u00edpad\u011b \u017ee nen\u00ed blesk p\u0159\u00edmo nad n\u00e1mi, vid\u00edme nejprve z\u00e1\u0159i blesku a pak teprve sly\u0161\u00edme hrom.<\/p>\n<p>Rychlost zvuku je p\u0159ibli\u017ene 340 m\/s. To znamen\u00e1, \u017ee uraz\u00ed za 3 sekundy 1 kilometr. Proto se d\u00e1 odhadhnout, jak daleko je blesk vzd\u00e1len\u00fd od m\u00edsta, ze kter\u00e9ho jej pozorujeme.<\/p>\n<h3>Blesk je n\u011bkdy zcela nep\u0159edv\u00eddateln\u00fd<\/h3>\n<ul>\n<li><a href=\"http:\/\/www.telegraph.co.uk\/news\/newstopics\/howaboutthat\/8512476\/Plane-struck-by-lightning-coming-into-Heathrow.html\">z\u00e1sah letadla<\/a><\/li>\n<li><a href=\"http:\/\/zpravy.idnes.cz\/blesk-tezce-zranil-dva-mladiky-jeden-se-probral-z-bezvedomi-a-zavolal-pomoc-1ud-\/krimi.aspx?c=A100522_173317_krimi_js\">2 mlad\u00edci u Hostinn\u00e9ho na Trutnovsku<\/a><\/li>\n<li><a href=\"http:\/\/zpravy.idnes.cz\/blesk-zabil-v-africkem-burundi-deset-skolaku-dalsi-popalil-pnb-\/zahranicni.aspx?c=A110219_092520_zahranicni_fih\">\u0161kola v Burundi<\/a><\/li>\n<\/ul>\n<h3>Blesk m\u016f\u017ee vzniknout i u elektrick\u00e9ho nap\u011bt\u00ed<\/h3>\n<ul>\n<li><a href=\"http:\/\/www.novinky.cz\/krimi\/276570-kamarada-bagrem-vyzdvihl-k-dratum-vysokeho-napeti-vyboj-ho-usmrtil.html\">Z\u00e1sah elektrick\u00fdm vedn\u00edm<\/a><\/li>\n<li><a href=\"http:\/\/zpravy.idnes.cz\/mrtvola-na-lokomotive-v-decine-dzz-\/krimi.aspx?c=A130416_095528_usti-zpravy_alh\">Smrt na lokomotiv\u011b<\/a><\/li>\n<li><a href=\"http:\/\/vary.idnes.cz\/smrt-po-zasahu-elektrickym-proudem-d63-\/vary-zpravy.aspx?c=A130824_141505_vary-zpravy_mav\">Usmrcen\u00ed na elektrick\u00e9m veden\u00ed<\/a>\n<\/ul>\n<div class=\"bonus\">\n<h2>Pr\u00e9miov\u00e9 ot\u00e1zky<\/h2>\n<p>1. Jak daleko je od n\u00e1s blesk, kdy\u017e hrom ude\u0159il 8 sekund po z\u00e1blesku?<br \/>\n2. Za jak dlouho usly\u0161\u00edme blesk, kter\u00fd ude\u0159\u00ed nad n\u00e1mi ve v\u00fd\u0161ce 4,2 km?<\/p>\n<p><em>Odpov\u011b\u010f zapi\u0161 ve form\u011b \u0159e\u0161en\u00ed p\u0159\u00edkladu.<\/em>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Blesk je sv\u011bteln\u00fd projev bou\u0159liv\u00e9 cesty elektricky nabit\u00fdch \u010d\u00e1stic do m\u00edsta, kter\u00e9 je opa\u010dn\u011b nabit\u00e9. P\u0159esto\u017ee trv\u00e1 jen velmi kr\u00e1tkou dobu, uvoln\u00ed obrovsk\u00e9 mno\u017estv\u00ed energie. &#8230;. <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[57,5,13],"tags":[17],"class_list":["post-745","post","type-post","status-publish","format-standard","hentry","category-6-rocnik","category-elektrina-a-magnetismus","category-zajimavosti","tag-video"],"_links":{"self":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts\/745","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=745"}],"version-history":[{"count":0,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts\/745\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=745"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=745"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=745"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}