{"id":16708,"date":"2024-09-20T12:21:32","date_gmt":"2024-09-20T15:21:32","guid":{"rendered":"https:\/\/xequematenem.com.br\/blog\/?p=16708"},"modified":"2024-09-20T12:23:32","modified_gmt":"2024-09-20T15:23:32","slug":"questao-126-enem-2019","status":"publish","type":"post","link":"https:\/\/xequematenem.com.br\/blog\/questao-126-enem-2019\/","title":{"rendered":"Quest\u00e3o 126 -ENEM 2019"},"content":{"rendered":"\n<p>Uma casa tem um cabo el\u00e9trico mal dimensionado, de resist\u00eancia igual a 10 \u03a9, que a conecta \u00e0 rede el\u00e9trica de 120 V. Nessa casa, cinco l\u00e2mpadas, de resist\u00eancia igual a 200 \u03a9, est\u00e3o conectadas ao mesmo circuito que uma televis\u00e3o de resist\u00eancia igual a 50 \u03a9, conforme ilustrado no esquema. A televis\u00e3o funciona apenas com tens\u00e3o entre 90 V e 130 V.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img fetchpriority=\"high\" decoding=\"async\" width=\"355\" height=\"153\" src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-519.png\" alt=\"\" class=\"wp-image-16709\" title=\"\" srcset=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-519.png 355w, https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-519-300x129.png 300w\" sizes=\"(max-width: 355px) 100vw, 355px\" \/><\/figure>\n\n\n\n<p>O n\u00famero m\u00e1ximo de l\u00e2mpadas que podem ser ligadas sem que a televis\u00e3o pare de funcionar \u00e9:&nbsp;<\/p>\n\n\n\n<p>A) 1.&nbsp;<\/p>\n\n\n\n<p>B) 2.&nbsp;<\/p>\n\n\n\n<p>C) 3.&nbsp;<\/p>\n\n\n\n<p>D) 4.&nbsp;<\/p>\n\n\n\n<p>E) 5.<\/p>\n\n\n\n<p class=\"has-text-align-center has-large-font-size\"><strong>Solu\u00e7\u00e3o<\/strong><\/p>\n\n\n\n<p>A corrente que atravessa o cabo \u00e9 distribu\u00edda para cada componente. Ent\u00e3o, da primeira lei de Kirchhoff<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"203\" height=\"39\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-520.png\" alt=\"\" class=\"wp-image-16710 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 203px; --smush-placeholder-aspect-ratio: 203\/39;\"><\/figure>\n\n\n\n<p>como a corrente se distribui de forma igual entre os N resistores R<sub>1<\/sub>\u00a0<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"170\" height=\"153\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-521.png\" alt=\"\" class=\"wp-image-16711 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 170px; --smush-placeholder-aspect-ratio: 170\/153;\"><\/figure>\n\n\n\n<p>Agora, a tens\u00e3o U<sub>AB<\/sub>&nbsp; entre quaisquer dois pontos A e B \u00e9 igual \u00e0 tens\u00e3o U<sub>TV<\/sub>, pois est\u00e3o em paralelo. Dessa forma,<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"126\" height=\"31\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-522.png\" alt=\"\" class=\"wp-image-16712 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 126px; --smush-placeholder-aspect-ratio: 126\/31;\"><\/figure>\n\n\n\n<p>e a tens\u00e3o U<sub>CA<\/sub> \u00e9 igual a tens\u00e3o U<sub>C<\/sub><\/p>\n\n\n\n<p>Para garantir que a TV funcione, sua tens\u00e3o n\u00e3o deve ser menor que 90 V. Ent\u00e3o, considerando a menor tens\u00e3o poss\u00edvel para o funcionamento da TV, U<sub>TV<\/sub> = 90V a segunda lei de Kirchhoff nos fornece a tens\u00e3o el\u00e9trica U<sub>C<\/sub> no cabo:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"167\" height=\"176\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-523.png\" alt=\"\" class=\"wp-image-16713 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 167px; --smush-placeholder-aspect-ratio: 167\/176;\"><\/figure>\n\n\n\n<p>Agora, utilizando a Lei de Ohm, a corrente no cabo i<sub>C<\/sub> \u00e9 calculada como:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"146\" height=\"167\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-524.png\" alt=\"\" class=\"wp-image-16714 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 146px; --smush-placeholder-aspect-ratio: 146\/167;\"><\/figure>\n\n\n\n<p>Da mesma forma,&nbsp;<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"161\" height=\"99\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-525.png\" alt=\"\" class=\"wp-image-16715 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 161px; --smush-placeholder-aspect-ratio: 161\/99;\"><\/figure>\n\n\n\n<p>E mais uma vez<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"126\" height=\"107\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-526.png\" alt=\"\" class=\"wp-image-16716 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 126px; --smush-placeholder-aspect-ratio: 126\/107;\"><\/figure>\n\n\n\n<p>Concluindo:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"154\" height=\"49\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-527.png\" alt=\"\" class=\"wp-image-16717 lazyload\" title=\"\" data-srcset=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-527.png 154w, https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-527-150x49.png 150w\" data-sizes=\"(max-width: 154px) 100vw, 154px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 154px; --smush-placeholder-aspect-ratio: 154\/49;\" \/><\/figure>\n\n\n\n<p><strong>Alternativa B<\/strong><\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Uma casa tem um cabo el\u00e9trico mal dimensionado, de resist\u00eancia igual a 10 \u03a9, que a conecta \u00e0 rede el\u00e9trica de 120 V. Nessa casa, cinco l\u00e2mpadas, de resist\u00eancia igual a 200 \u03a9, est\u00e3o conectadas ao mesmo circuito que uma televis\u00e3o de resist\u00eancia igual a 50 \u03a9, conforme ilustrado no esquema. A televis\u00e3o funciona apenas [&hellip;]<\/p>\n","protected":false},"author":11,"featured_media":16709,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17,19],"tags":[],"area-do-conhecimento":[116,121],"assunto":[],"class_list":["post-16708","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-questoes-do-enem","category-19","area-do-conhecimento-ciencias-da-natureza-e-suas-tecnologias","area-do-conhecimento-fisica"],"_links":{"self":[{"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/posts\/16708","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/comments?post=16708"}],"version-history":[{"count":2,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/posts\/16708\/revisions"}],"predecessor-version":[{"id":16719,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/posts\/16708\/revisions\/16719"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/media\/16709"}],"wp:attachment":[{"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/media?parent=16708"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/categories?post=16708"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/tags?post=16708"},{"taxonomy":"area-do-conhecimento","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/area-do-conhecimento?post=16708"},{"taxonomy":"assunto","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/assunto?post=16708"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}