Điện trở. Định luật Ohm

Home Lớp 9 Khoa học tự nhiên 9 - sách kết nối tri thức Bài 11: Điện trở. Định luật OhmBài tập trung bình

{"common":{"save":0,"post_id":"8241","level":2,"total":10,"point":10,"point_extra":0},"segment":[{"id":"9362","post_id":"8241","mon_id":"1159533","chapter_id":"1159663","question":"Có m\u1ed9t \u0111o\u1ea1n dây d\u1eabn có chi\u1ec1u dài $l$<\/span>, ti\u1ebft di\u1ec7n $S$<\/span>, và \u0111i\u1ec7n tr\u1edf su\u1ea5t $\u03c1$<\/span>. N\u1ebfu chi\u1ec1u dài t\u0103ng g\u1ea5p \u0111ôi và ti\u1ebft di\u1ec7n t\u0103ng g\u1ea5p ba, \u0111i\u1ec7n tr\u1edf c\u1ee7a dây s\u1ebd thay \u0111\u1ed5i nh\u01b0 th\u1ebf nào?<\/p>","options":["A. T\u0103ng 1,5 l\u1ea7n","B. Gi\u1ea3m 2\/3 l\u1ea7n","C. T\u0103ng 2\/3 l\u1ea7n","D. Gi\u1ea3m 1\/3 l\u1ea7n"],"correct":"2","level":"2","hint":"","answer":"\u0110áp án: B. Gi\u1ea3m 2\/3 l\u1ea7n<\/p>Gi\u1ea3i thích:<\/p>\u0110i\u1ec7n tr\u1edf \u0111\u01b0\u1ee3c tính b\u1edfi: $R = \u03c1 . {l \\over S}$<\/span><\/p>Khi $l$<\/span> t\u0103ng g\u1ea5p \u0111ôi và $S$<\/span> t\u0103ng g\u1ea5p ba: $R = \u03c1. {2l \\over 3S} = {2 \\over 3}R$<\/span><\/p>\u0110i\u1ec7n tr\u1edf gi\u1ea3m 2\/3 l\u1ea7n.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"125","test":"0","date":"2024-12-26 16:45:35","option_type":"txt","len":1},{"id":"9363","post_id":"8241","mon_id":"1159533","chapter_id":"1159663","question":"M\u1ed9t \u0111o\u1ea1n m\u1ea1ch có \u0111i\u1ec7n tr\u1edf R = 10 Ω. Khi hi\u1ec7u \u0111i\u1ec7n th\u1ebf \u0111\u1eb7t vào hai \u0111\u1ea7u m\u1ea1ch t\u0103ng t\u1eeb 5V lên 10V, c\u01b0\u1eddng \u0111\u1ed9 dòng \u0111i\u1ec7n qua m\u1ea1ch s\u1ebd:<\/p>","options":["A. Gi\u1ea3m \u0111i m\u1ed9t n\u1eeda.","B. Không thay \u0111\u1ed5i.","C. T\u0103ng g\u1ea5p \u0111ôi.","D. T\u0103ng g\u1ea5p b\u1ed1n."],"correct":"3","level":"2","hint":"","answer":"\u0110áp án: C. T\u0103ng g\u1ea5p \u0111ôi<\/p>Gi\u1ea3i thích:<\/p>Theo \u0111\u1ecbnh lu\u1eadt Ohm: $I = {U \\over R}$<\/span><\/p>Khi $U$<\/span> t\u0103ng t\u1eeb 5V lên 10V, $I$<\/span> c\u0169ng t\u0103ng t\u1eeb 0,5A lên 1A, t\u1ee9c là $I$<\/span> t\u0103ng g\u1ea5p \u0111ôi. <\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"125","test":"0","date":"2024-12-26 16:50:35","option_type":"txt","len":2},{"id":"9364","post_id":"8241","mon_id":"1159533","chapter_id":"1159663","question":"M\u1ed9t dây d\u1eabn có chi\u1ec1u dài 2m, ti\u1ebft di\u1ec7n 1$mm^2$<\/span>, và \u0111i\u1ec7n tr\u1edf su\u1ea5t $\u03c1 = 1,7.10^{-8}\\ \u03a9.m$<\/span>. \u0110i\u1ec7n tr\u1edf c\u1ee7a dây là:<\/p>","options":["A. 0,034 $\u03a9$<\/span> ","B. 0,17 $\u03a9$<\/span>","C. 0,34 $\u03a9$<\/span>","D. 1,7 $\u03a9$<\/span>"],"correct":"1","level":"2","hint":"","answer":"\u0110áp án: A. 0,034 $\u03a9$<\/span><\/p>Gi\u1ea3i thích:<\/p>S\u1eed d\u1ee5ng công th\u1ee9c: $R = \u03c1. {l \\over S} = 1,7.10^{-8}. { 2 \\over {1.10^{-6}}} = 0,034$<\/span> $\u03a9$<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"125","test":"0","date":"2024-12-26 16:58:17","option_type":"math","len":0}]}