{"segment":[{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai10/lv2/img\/1.jpg'\/><\/center>Cho m\u1ea1ch \u0111i\u1ec7n c\u00f3 s\u01a1 \u0111\u1ed3 nh\u01b0 h\u00ecnh v\u1ebd, trong \u0111\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf gi\u1eefa hai \u0111i\u1ec3m A v\u00e0 B \u0111\u01b0\u1ee3c gi\u1eef kh\u00f4ng \u0111\u1ed5i v\u00e0 \u0111\u00e8n s\u00e1ng b\u00ecnh th\u01b0\u1eddng khi bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf b\u1eb1ng 0. C\u00e2u ph\u00e1t bi\u1ec3u n\u00e0o d\u01b0\u1edbi \u0111\u00e2y l\u00e0 \u0111\u00fang? ","select":["A. \u0110\u00e8n s\u00e1ng m\u1ea1nh l\u00ean khi di chuy\u1ec3n con ch\u1ea1y c\u1ee7a bi\u1ebfn tr\u1edf v\u1ec1 \u0111\u1ea7u M.","B. \u0110\u00e8n s\u00e1ng y\u1ebfu \u0111i khi di chuy\u1ec3n con ch\u1ea1y c\u1ee7a bi\u1ebfn tr\u1edf v\u1ec1 \u0111\u1ea7u M.","C. \u0110\u00e8n s\u00e1ng m\u1ea1nh l\u00ean khi di chuy\u1ec3n con ch\u1ea1y c\u1ee7a bi\u1ebfn tr\u1edf v\u1ec1 \u0111\u1ea7u N.","D. C\u1ea3 ba c\u00e2u tr\u00ean \u0111\u1ec1u kh\u00f4ng \u0111\u00fang."],"hint":"","explain":"<span class='basic_left'>\u0110\u00e8n s\u00e1ng m\u1ea1nh l\u00ean khi chuy\u1ec3n con ch\u1ea1y c\u1ee7a bi\u1ebfn tr\u1edf v\u1ec1 \u0111\u1ea7u M. V\u00ec d\u00f2ng \u0111i\u1ec7n c\u00f3 chi\u1ec1u \u0111i t\u1eeb c\u1ef1c (+) qua d\u00e2y d\u1eabn qua c\u00e1c thi\u1ebft b\u1ecb r\u1ed3i v\u1ec1 c\u1ef1c (-) n\u00ean \u1edf \u0111\u1ea7u M khi con ch\u1ea1y ch\u01b0a d\u1ecbch chuy\u1ec3n chi\u1ec1u d\u00e0i ch\u01b0a thay \u0111\u1ed5i th\u00ec \u0111i\u1ec7n tr\u1edf l\u00e0 nh\u1ecf nh\u1ea5t n\u00ean \u0111\u00e8n s\u00e1ng nh\u1ea5t.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":1}]}],"id_ques":2831},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai10/lv2/img\/2.jpg'\/><\/center>Hi\u1ec7u \u0111i\u1ec7n th\u1ebf U trong m\u1ea1ch \u0111i\u1ec7n c\u00f3 s\u01a1 \u0111\u1ed3 nh\u01b0 h\u00ecnh v\u1ebd \u0111\u01b0\u1ee3c gi\u1eef kh\u00f4ng \u0111\u1ed5i. Khi d\u1ecbch chuy\u1ec3n con ch\u1ea1y c\u1ee7a bi\u1ebfn tr\u1edf ti\u1ebfn d\u1ea7n v\u1ec1 ph\u00eda \u0111\u1ea7u N th\u00ec ch\u1ec9 s\u1ed1 ampe k\u1ebf s\u1ebd thay \u0111\u1ed5i nh\u01b0 th\u1ebf n\u00e0o? ","select":["A. Gi\u1ea3m d\u1ea7n \u0111i.","B. T\u0103ng d\u1ea7n l\u00ean.","C. Kh\u00f4ng thay \u0111\u1ed5i.","D. L\u00fac \u0111\u1ea7u gi\u1ea3m d\u1ea7n \u0111i, sau \u0111\u00f3 t\u0103ng d\u1ea7n."],"hint":"","explain":"<span class='basic_left'>Chi\u1ec1u d\u00f2ng \u0111i\u1ec7n \u0111i t\u1eeb c\u1ef1c (+) qua d\u00e2y d\u1eabn, thi\u1ebft b\u1ecb \u0111i\u1ec7n r\u1ed3i v\u1ec1 c\u1ef1c (-) c\u1ee7a ngu\u1ed3n \u0111i\u1ec7n. Khi con ch\u1ea1y ti\u1ebfn d\u1ea7n v\u1ec1 \u0111\u1ea7u N chi\u1ec1u d\u00e0i c\u1ee7a bi\u1ebfn tr\u1edf t\u0103ng d\u1ea7n l\u00e0m cho \u0111i\u1ec7n tr\u1edf c\u1ee7a d\u00e2y d\u1eabn t\u0103ng d\u1ea7n, khi U kh\u00f4ng \u0111\u1ed5i th\u00ec s\u1ed1 ch\u1ec9 c\u1ee7a ampe k\u1ebf t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi \u0111i\u1ec7n tr\u1edf n\u00ean n\u00f3 s\u1ebd gi\u1ea3m d\u1ea7n \u0111i.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2832},{"time":24,"part":[{"title":"","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"C\u00e2u ph\u00e1t bi\u1ec3u n\u00e0o d\u01b0\u1edbi \u0111\u00e2y v\u1ec1 bi\u1ebfn tr\u1edf l\u00e0 kh\u00f4ng \u0111\u00fang?","select":["A. Bi\u1ebfn tr\u1edf l\u00e0 \u0111i\u1ec7n tr\u1edf c\u00f3 th\u1ec3 thay \u0111\u1ed5i tr\u1ecb s\u1ed1.","B. Bi\u1ebfn tr\u1edf l\u00e0 d\u1ee5ng c\u1ee5 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 thay \u0111\u1ed5i c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n.","C. Bi\u1ebfn tr\u1edf l\u00e0 d\u1ee5ng c\u1ee5 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 thay \u0111\u1ed5i hi\u1ec7u \u0111i\u1ec7n th\u1ebf gi\u1eefa hai \u0111\u1ea7u d\u1ee5ng c\u1ee5 \u0111i\u1ec7n.","D. Bi\u1ebfn tr\u1edf l\u00e0 d\u1ee5ng c\u1ee5 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 \u0111\u1ed5i chi\u1ec1u d\u00f2ng \u0111i\u1ec7n trong m\u1ea1ch."],"hint":"","explain":"<span class='basic_left'>Bi\u1ebfn tr\u1edf l\u00e0 \u0111i\u1ec7n tr\u1edf c\u00f3 th\u1ec3 thay \u0111\u1ed5i tr\u1ecb s\u1ed1 v\u00e0 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 \u0111i\u1ec1u ch\u1ec9nh c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n trong m\u1ea1ch.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":1}]}],"id_ques":2833},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"Tr\u00ean m\u1ed9t bi\u1ebfn tr\u1edf c\u00f3 ghi 30\u2126-2,5A. C\u00e1c s\u1ed1 ghi n\u00e0y c\u00f3 \u00fd ngh\u0129a n\u00e0o d\u01b0\u1edbi \u0111\u00e2y?","select":["A. Bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf nh\u1ecf nh\u1ea5t l\u00e0 30\u2126 v\u00e0 ch\u1ecbu \u0111\u01b0\u1ee3c d\u00f2ng \u0111i\u1ec7n c\u00f3 c\u01b0\u1eddng \u0111\u1ed9 nh\u1ecf nh\u1ea5t l\u00e0 2,5A.","B. Bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf nh\u1ecf nh\u1ea5t l\u00e0 30\u2126 v\u00e0 ch\u1ecbu \u0111\u01b0\u1ee3c d\u00f2ng \u0111i\u1ec7n c\u00f3 c\u01b0\u1eddng \u0111\u1ed9 l\u1edbn nh\u1ea5t l\u00e0 2,5A.","C. Bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t l\u00e0 30\u2126 v\u00e0 ch\u1ecbu \u0111\u01b0\u1ee3c d\u00f2ng \u0111i\u1ec7n c\u00f3 c\u01b0\u1eddng \u0111\u1ed9 l\u1edbn nh\u1ea5t l\u00e0 2,5A.","D. Bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t l\u00e0 30\u2126 v\u00e0 ch\u1ecbu \u0111\u01b0\u1ee3c d\u00f2ng \u0111i\u1ec7n c\u00f3 c\u01b0\u1eddng \u0111\u1ed9 nh\u1ecf nh\u1ea5t l\u00e0 2,5A."],"hint":"","explain":"<span class='basic_left'>Tr\u00ean m\u1ed9t bi\u1ebfn tr\u1edf c\u00f3 ghi 30\u2126-2,5A. C\u00e1c s\u1ed1 ghi n\u00e0y c\u00f3 \u00fd ngh\u0129a l\u00e0:<br\/> Bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t l\u00e0 30\u2126 v\u00e0 ch\u1ecbu \u0111\u01b0\u1ee3c d\u00f2ng \u0111i\u1ec7n c\u00f3 c\u01b0\u1eddng \u0111\u1ed9 l\u1edbn nh\u1ea5t l\u00e0 2,5A. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":1}]}],"id_ques":2834},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"C\u1ea7n l\u00e0m m\u1ed9t bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t l\u00e0 30\u03a9 b\u1eb1ng d\u00e2y d\u1eabn Nik\u00ealin c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t $0,4\\times {{10}^{-6}}\\Omega m$v\u00e0 ti\u1ebft di\u1ec7n $0,5m{{m}^{2}}$. T\u00ednh chi\u1ec1u d\u00e0i c\u1ee7a d\u00e2y d\u1eabn.","select":["A. 18m","B. 37,5 m","C. 27m","D. 38m"],"hint":"","explain":"<span class='basic_left'>Chi\u1ec1u d\u00e0i d\u00e2y d\u1eabn l\u00e0: $l=\\dfrac{R\\times S}{\\rho }=\\dfrac{30\\times 0,5\\times {{10}^{-6}}}{0,4\\times {{10}^{-6}}}=37,5m$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2835},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"Cu\u1ed9n d\u00e2y c\u1ee7a m\u1ed9t bi\u1ebfn tr\u1edf con ch\u1ea1y \u0111\u01b0\u1ee3c l\u00e0m b\u1eb1ng h\u1ee3p kim Nik\u00ealin c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t $0,4\\times {{10}^{-6}}\\Omega m$, c\u00f3 ti\u1ebft di\u1ec7n \u0111\u1ec1u l\u00e0 $0,6m{{m}^{2}}$v\u00e0 g\u1ed3m 500 v\u00f2ng qu\u1ea5n quanh l\u00f5i s\u1ee9 tr\u1ee5 tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh 4cm. T\u00ednh \u0111i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t c\u1ee7a bi\u1ebfn tr\u1edf n\u00e0y.","select":["A. 66,7\u03a9","B. 33,3\u03a9","C. 42,4\u03a9","D. 41,9\u03a9"],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t c\u1ee7a bi\u1ebfn tr\u1edf l\u00e0: ${{R}_{\\max }}=\\rho \\times \\dfrac{l}{S}=\\rho \\times \\dfrac{N\\times 3,14\\times d}{S}=0,4\\times {{10}^{-6}}\\times \\dfrac{500\\times 3,14\\times 0,04}{0,6\\times {{10}^{-6}}}=41,9\\Omega $<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2836},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"Cu\u1ed9n d\u00e2y c\u1ee7a m\u1ed9t bi\u1ebfn tr\u1edf con ch\u1ea1y \u0111\u01b0\u1ee3c l\u00e0m b\u1eb1ng h\u1ee3p kim Nik\u00ealin c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t $0,4\\times {{10}^{-6}}\\Omega m$, c\u00f3 ti\u1ebft di\u1ec7n \u0111\u1ec1u l\u00e0 $0,6m{{m}^{2}}$v\u00e0 g\u1ed3m 500 v\u00f2ng qu\u1ea5n quanh l\u00f5i s\u1ee9 tr\u1ee5 tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh 4cm. Hi\u1ec7u \u0111i\u1ec7n th\u1ebf l\u1edbn nh\u1ea5t \u0111\u01b0\u1ee3c ph\u00e9p \u0111\u1eb7t l\u00ean hai \u0111\u1ea7u cu\u1ed9n d\u00e2y c\u1ee7a bi\u1ebfn tr\u1edf l\u00e0 67V. H\u1ecfi bi\u1ebfn tr\u1edf n\u00e0y ch\u1ecbu \u0111\u01b0\u1ee3c d\u00f2ng \u0111i\u1ec7n c\u00f3 c\u01b0\u1eddng \u0111\u1ed9 l\u1edbn nh\u1ea5t l\u00e0 bao nhi\u00eau?","select":["A. 1,5A","B. 1,6A","C. 1,2A","D. 2,4A"],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t c\u1ee7a bi\u1ebfn tr\u1edf l\u00e0:<br\/>${{R}_{\\max }}=\\rho \\times \\dfrac{l}{S}=\\rho \\times \\dfrac{N\\times 3,14\\times d}{S}=0,4\\times {{10}^{-6}}\\times \\dfrac{500\\times 3,14\\times 0,04}{0,6\\times {{10}^{-6}}}=41,9\\Omega $<br\/>Bi\u1ebfn tr\u1edf ch\u1ecbu \u0111\u01b0\u1ee3c d\u00f2ng \u0111i\u1ec7n c\u00f3 c\u01b0\u1eddng \u0111\u1ed9 l\u1edbn nh\u1ea5t l\u00e0:<br\/>${{I}_{\\max }}=\\dfrac{{{U}_{\\max }}}{{{R}_{\\max }}}=\\dfrac{67}{41,9}=1,6A$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2837},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"M\u1ed9t b\u00f3ng \u0111\u00e8n c\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf \u0111\u1ecbnh m\u1ee9c 2,5V v\u00e0 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n \u0111\u1ecbnh m\u1ee9c 0,4A \u0111\u01b0\u1ee3c m\u1eafc v\u1edbi m\u1ed9t bi\u1ebfn tr\u1edf con ch\u1ea1y \u0111\u1ec3 s\u1eed d\u1ee5ng v\u1edbi ngu\u1ed3n \u0111i\u1ec7n c\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf kh\u00f4ng \u0111\u1ed5i 12V. \u0110\u1ec3 \u0111\u00e8n s\u00e1ng b\u00ecnh th\u01b0\u1eddng th\u00ec ph\u1ea3i \u0111i\u1ec1u ch\u1ec9nh bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u00e0 bao nhi\u00eau?","select":["A. 33,7\u03a9","B. 23,6\u03a9","C. 23,75\u03a9","D. 22,5\u03a9"],"hint":"","explain":"<span class='basic_left'>\u0110\u00e8n s\u00e1ng b\u00ecnh th\u01b0\u1eddng khi bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u00e0: ${{R}_{bt}}=\\dfrac{12-2,5}{0,4}=23,75\\Omega $<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2838},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"M\u1ed9t b\u00f3ng \u0111\u00e8n c\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf \u0111\u1ecbnh m\u1ee9c 2,5V v\u00e0 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n \u0111\u1ecbnh m\u1ee9c 0,4A \u0111\u01b0\u1ee3c m\u1eafc v\u1edbi m\u1ed9t bi\u1ebfn tr\u1edf con ch\u1ea1y \u0111\u1ec3 s\u1eed d\u1ee5ng v\u1edbi ngu\u1ed3n \u0111i\u1ec7n c\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf kh\u00f4ng \u0111\u1ed5i 12V. N\u1ebfu bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t l\u00e0 40\u03a9 th\u00ec khi \u0111\u00e8n s\u00e1ng b\u00ecnh th\u01b0\u1eddng d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua bao nhi\u00eau ph\u1ea7n tr\u0103m (%) t\u1ed5ng s\u1ed1 v\u00f2ng d\u00e2y c\u1ee7a bi\u1ebfn tr\u1edf?","select":["A. 28%","B. 54%","C. 56%","D. 59%"],"hint":"","explain":"<span class='basic_left'>\u0110\u00e8n s\u00e1ng b\u00ecnh th\u01b0\u1eddng khi bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u00e0: ${{R}_{bt}}=\\dfrac{12-2,5}{0,4}=23,75\\Omega $<br\/>S\u1ed1 ph\u1ea7n tr\u0103m v\u00f2ng d\u00e2y c\u1ee7a bi\u1ebfn tr\u1edf c\u00f3 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua l\u00e0: $n=\\dfrac{23,75}{40}=0,59375=59%$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2839},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai10/lv2/img\/10.jpg'\/><\/center>M\u1ed9t bi\u1ebfn tr\u1edf ${{R}_{b}}$ c\u00f3 gi\u00e1 tr\u1ecb l\u1edbn nh\u1ea5t l\u00e0 30\u2126 \u0111\u01b0\u1ee3c m\u1eafc v\u1edbi hai \u0111i\u1ec7n tr\u1edf ${{R}_{1}}=15\\Omega $v\u00e0 ${{R}_{2}}=10\\Omega $th\u00e0nh m\u1ea1ch c\u00f3 s\u01a1 \u0111\u1ed3 nh\u01b0 h\u00ecnh v\u1ebd , trong \u0111\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf kh\u00f4ng \u0111\u1ed5i U=4,5V. H\u1ecfi khi \u0111i\u1ec1u ch\u1ec9nh bi\u1ebfn tr\u1edf th\u00ec c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua \u0111i\u1ec7n tr\u1edf ${{R}_{1}}$ c\u00f3 gi\u00e1 tr\u1ecb l\u1edbn nh\u1ea5t ${{I}_{\\max }}$ v\u00e0 nh\u1ecf nh\u1ea5t ${{I}_{\\min }}$l\u00e0 bao nhi\u00eau?","select":["A. 0,5A v\u00e0 0,4A","B. 0,2A v\u00e0 0,1A","C. 0,3A v\u00e0 0,2A","D. 0,4A v\u00e0 0,3A"],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf ${{R}_{2}}$ v\u00e0 ${{R}_{b}}$ l\u00e0: ${{R}_{bt}}=\\dfrac{{{R}_{2}}\\times {{R}_{b}}}{{{R}_{2}}+{{R}_{b}}}=\\dfrac{10\\times 30}{10+30}=7,5\\Omega $<br\/>\u0110i\u1ec7n tr\u1edf t\u01b0\u01a1ng \u0111\u01b0\u01a1ng: ${{R}_{td}}={{R}_{1}}+{{R}_{2b}}=15+7,5=22,5\\Omega $<br\/>C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n nh\u1ecf nh\u1ea5t: ${{I}_{\\min }}=\\dfrac{U}{{{R}_{td}}}=\\dfrac{4,5}{22,5}=0,2A$<br\/>C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n l\u1edbn nh\u1ea5t (${{R}_{b}}=0$):${{I}_{\\max }}={{I}_{1}}=\\dfrac{U}{{{R}_{1}}}=\\dfrac{4,5}{15}=0,3A$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2840},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"Ng\u01b0\u1eddi ta d\u00f9ng d\u00e2y nicrom c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t l\u00e0 $1,1\\times {{10}^{-6}}\\Omega m$v\u00e0 c\u00f3 \u0111\u01b0\u1eddng k\u00ednh ti\u1ebft di\u1ec7n l\u00e0 ${{d}_{1}}=0,8mm$\u0111\u1ec3 qu\u1ea5n m\u1ed9t bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t l\u00e0 20\u2126. T\u00ednh \u0111\u1ed9 d\u00e0i ${{l}_{1}}$ c\u1ee7a \u0111o\u1ea1n d\u00e2y nicrom c\u1ea7n d\u00f9ng \u0111\u1ec3 qu\u1ea5n bi\u1ebfn tr\u1edf n\u00f3i tr\u00ean.","select":["A. 91,3cm","B. 91,3m","C. 913mm","D. 913cm"],"hint":"","explain":"<span class='basic_left'>Ti\u1ebft di\u1ec7n c\u1ee7a d\u00e2y nicrom: $S=\\dfrac{3,14\\times {{d}^{2}}}{4}=\\dfrac{3,14\\times {{\\left( 0,8 \\right)}^{2}}}{4}=0,5024m{{m}^{2}}$<br\/>Chi\u1ec1u d\u00e0i c\u1ee7a d\u00e2y nicrom: $l=\\dfrac{R\\times S}{\\rho }=\\dfrac{20\\times 0,5024\\times {{10}^{-6}}}{0,4\\times {{10}^{-6}}}=9,13m=913cm$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2841},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"Tr\u01b0\u1edbc khi m\u1eafc bi\u1ebfn tr\u1edf v\u00e0o m\u1ea1ch \u0111\u1ec3 \u0111i\u1ec1u ch\u1ec9nh c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n th\u00ec c\u1ea7n \u0111i\u1ec1u ch\u1ec9nh bi\u1ebfn tr\u1edf c\u00f3 gi\u00e1 tr\u1ecb n\u00e0o d\u01b0\u1edbi \u0111\u00e2y? ","select":["A. C\u00f3 gi\u00e1 tr\u1ecb 0.","B. C\u00f3 gi\u00e1 tr\u1ecb nh\u1ecf.","C. C\u00f3 gi\u00e1 tr\u1ecb l\u1edbn.","D. C\u00f3 gi\u00e1 tr\u1ecb l\u1edbn nh\u1ea5t."],"hint":"","explain":"<span class='basic_left'>Tr\u01b0\u1edbc khi m\u1eafc bi\u1ebfn tr\u1edf v\u00e0o m\u1ea1ch \u0111\u1ec3 \u0111i\u1ec1u ch\u1ec9nh c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n th\u00ec c\u1ea7n \u0111i\u1ec1u ch\u1ec9nh bi\u1ebfn tr\u1edf c\u00f3 gi\u00e1 tr\u1ecb l\u1edbn nh\u1ea5t.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2842},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"Tr\u00ean m\u1ed9t bi\u1ebfn tr\u1edf con ch\u1ea1y c\u00f3 ghi 50\u03a9 \u2013 2,5A. T\u00ednh hi\u1ec7u \u0111i\u1ec7n th\u1ebf l\u1edbn nh\u1ea5t \u0111\u01b0\u1ee3c ph\u00e9p \u0111\u1eb7t l\u00ean hai \u0111\u1ea7u cu\u1ed9n d\u00e2y c\u1ee7a bi\u1ebfn tr\u1edf.","select":["A. 25V","B. 50V","C. 125V","D. 150V"],"hint":"","explain":"<span class='basic_left'>Hi\u1ec7u \u0111i\u1ec7n th\u1ebf l\u1edbn nh\u1ea5t \u0111\u01b0\u1ee3c \u0111\u1eb7t l\u00ean hai \u0111\u1ea7u cu\u1ed9n d\u00e2y: ${{U}_{\\max }}={{I}_{\\max }}\\times {{R}_{\\max }}=2,5\\times 50=125V$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2843},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"Tr\u00ean m\u1ed9t bi\u1ebfn tr\u1edf con ch\u1ea1y c\u00f3 ghi 50\u03a9 \u2013 2,5A. Bi\u1ebfn tr\u1edf \u0111\u01b0\u1ee3c l\u00e0m b\u1eb1ng d\u00e2y h\u1ee3p kim nicrom c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t $1,1\\times {{10}^{-6}}\\Omega m$v\u00e0 c\u00f3 chi\u1ec1u d\u00e0i 50m. T\u00ednh ti\u1ebft di\u1ec7n c\u1ee7a d\u00e2y d\u1eabn d\u00f9ng \u0111\u1ec3 l\u00e0m bi\u1ebfn tr\u1edf.","select":["A. $1,1m{{m}^{2}}$","B. $2,2m{{m}^{2}}$","C. $3,3m{{m}^{2}}$","D. $4,4m{{m}^{2}}$"],"hint":"","explain":"<span class='basic_left'>Ti\u1ebft di\u1ec7n c\u1ee7a d\u00e2y l\u00e0: $S=\\rho \\times \\dfrac{l}{R}=1,1\\times {{10}^{-6}}\\times \\dfrac{50}{50}=1,1\\times {{10}^{-6}}{{m}^{2}}=1,1m{{m}^{2}}$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2844},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai10/lv2/img\/15.png'\/><\/center>Trong m\u1ea1ch \u0111i\u1ec7n c\u00f3 s\u01a1 \u0111\u1ed3 v\u1ebd \u1edf h\u00ecnh v\u1ebd, ngu\u1ed3n \u0111i\u1ec7n c\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf kh\u00f4ng \u0111\u1ed5i 12V. \u0110i\u1ec1u ch\u1ec9nh con ch\u1ea1y c\u1ee7a bi\u1ebfn tr\u1edf \u0111\u1ec3 v\u00f4n k\u1ebf ch\u1ec9 6V th\u00ec ampe k\u1ebf ch\u1ec9 0,5A. H\u1ecfi khi \u0111\u00f3 bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u00e0 bao nhi\u00eau?","select":["A. 3\u03a9","B. 6\u03a9","C. 9\u03a9 ","D. 12\u03a9"],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf c\u1ee7a bi\u1ebfn tr\u1edf: ${{R}_{bt}}=\\dfrac{U-{{U}_{v}}}{I}=\\dfrac{12-6}{0,5}=12\\Omega $<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2845},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai10/lv2/img\/15.png'\/><\/center>Trong m\u1ea1ch \u0111i\u1ec7n c\u00f3 s\u01a1 \u0111\u1ed3 v\u1ebd \u1edf h\u00ecnh 10.2, ngu\u1ed3n \u0111i\u1ec7n c\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf kh\u00f4ng \u0111\u1ed5i 12V. \u0110i\u1ec1u ch\u1ec9nh con ch\u1ea1y c\u1ee7a bi\u1ebfn tr\u1edf \u0111\u1ec3 v\u00f4n k\u1ebf ch\u1ec9 6V th\u00ec ampe k\u1ebf ch\u1ec9 0,5A. Ph\u1ea3i \u0111i\u1ec1u ch\u1ec9nh bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u00e0 bao nhi\u00eau \u0111\u1ec3 v\u00f4n k\u1ebf ch\u1ec9 4,5V?","select":["A. 10\u03a9","B. 20\u03a9","C. 30\u03a9","D. 40\u03a9"],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf c\u1ee7a bi\u1ebfn tr\u1edf: ${{R}_{b1}}=\\dfrac{U-{{U}_{v}}}{I}=\\dfrac{12-6}{0,5}=12\\Omega $<br\/>C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua \u0111i\u1ec7n tr\u1edf R v\u00e0 bi\u1ebfn tr\u1edf khi \u0111\u00f3 l\u00e0: $I=\\dfrac{{{U}_{V}}}{R}=\\dfrac{4,5}{12}=0,375A$<br\/>\u0110\u1ec3 v\u00f4n k\u1ebf ch\u1ec9 4,5V th\u00ec \u0111i\u1ec7n tr\u1edf c\u1ee7a bi\u1ebfn tr\u1edf khi \u0111\u00f3 l\u00e0: ${{R}_{b2}}=\\dfrac{U}{I}-R=\\dfrac{12}{0,375}-12=20\\Omega $<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2846},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/vatly/bai10/lv2/img\/17.png'\/><\/center>Bi\u1ebfn tr\u1edf kh\u00f4ng c\u00f3 k\u00ed hi\u1ec7u s\u01a1 \u0111\u1ed3 n\u00e0o d\u01b0\u1edbi \u0111\u00e2y?","select":["A. Bi\u1ebfn tr\u1edf A","B. Bi\u1ebfn tr\u1edf B","C. Bi\u1ebfn tr\u1edf C","D. Bi\u1ebfn tr\u1edf D"],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2847},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"M\u1ed9t b\u00f3ng \u0111\u00e8n c\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf \u0111\u1ecbnh m\u1ee9c l\u00e0 3V v\u00e0 khi ra s\u00e1ng b\u00ecnh th\u01b0\u1eddng th\u00ec d\u00f2ng \u0111i\u1ec7n qua \u0111\u00e8n c\u00f3 c\u01b0\u1eddng \u0111\u1ed9 l\u00e0 0,32A. M\u1eafc b\u00f3ng \u0111\u00e8n n\u00e0y n\u1ed1i ti\u1ebfp v\u1edbi bi\u1ebfn tr\u1edf r\u1ed3i m\u1eafc v\u00e0o hi\u1ec7u \u0111i\u1ec7n th\u1ebf kh\u00f4ng \u0111\u1ed5i 12V. H\u1ecfi bi\u1ebfn tr\u1edf n\u00e0y ph\u1ea3i c\u00f3 gi\u00e1 tr\u1ecb l\u1edbn nh\u1ea5t t\u1ed1i thi\u1ec3u l\u00e0 bao nhi\u00eau \u0111\u1ec3 \u0111\u00e8n c\u00f3 th\u1ec3 s\u00e1ng b\u00ecnh th\u01b0\u1eddng?","select":["A. 21,185\u03a9","B. 28,125\u03a9","C. 28,25\u03a9","D. 12,5\u03a9"],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf t\u01b0\u01a1ng \u0111\u01b0\u01a1ng to\u00e0n m\u1ea1ch: ${{R}_{td}}=\\dfrac{U}{I}=\\dfrac{12}{0,32}=37,5\\Omega $<br\/>\u0110i\u1ec7n tr\u1edf c\u1ee7a b\u00f3ng \u0111\u00e8n: ${{R}_{\\text{D}}}=\\dfrac{U}{I}=\\dfrac{3}{0,32}=9,375\\Omega $<br\/>\u0110i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t c\u1ee7a bi\u1ebfn tr\u1edf: ${{R}_{b}}={{R}_{td}}-{{R}_{D}}=37,5-9,375=28,125\\Omega $<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2848},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"Ng\u01b0\u1eddi ta d\u00f9ng d\u00e2y nicrom c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t l\u00e0 $1,1\\times {{10}^{-6}}\\Omega m$v\u00e0 c\u00f3 \u0111\u01b0\u1eddng k\u00ednh ti\u1ebft di\u1ec7n l\u00e0 ${{d}_{1}}=0,8mm$\u0111\u1ec3 qu\u1ea5n m\u1ed9t bi\u1ebfn tr\u1edf c\u00f3 \u0111i\u1ec7n tr\u1edf l\u1edbn nh\u1ea5t l\u00e0 20\u2126. D\u00e2y nicrom c\u1ee7a bi\u1ebfn tr\u1edf n\u00e0y \u0111\u01b0\u1ee3c qu\u1ea5n th\u00e0nh m\u1ed9t l\u1edbp g\u1ed3m nh\u1eefng v\u00f2ng s\u00e1t nhau tr\u00ean m\u1ed9t l\u00f5i s\u1ee9 c\u00f3 \u0111\u01b0\u1eddng k\u00ednh ${{d}_{2}}=2,5cm$. T\u00ednh s\u1ed1 v\u00f2ng d\u00e2y.","select":["A. 113,3 v\u00f2ng","B. 161,6 v\u00f2ng","C. 136,3 v\u00f2ng","D. 116,3 v\u00f2ng"],"hint":"","explain":"<span class='basic_left'>Ti\u1ebft di\u1ec7n c\u1ee7a d\u00e2y nicrom: $S=\\dfrac{3,14\\times {{d}^{2}}}{4}=\\dfrac{3,14\\times {{\\left( 0,8 \\right)}^{2}}}{4}=0,5024m{{m}^{2}}$<br\/>Chi\u1ec1u d\u00e0i c\u1ee7a d\u00e2y nicrom: $l=\\dfrac{R\\times S}{\\rho }=\\dfrac{20\\times 0,5024\\times {{10}^{-6}}}{0,4\\times {{10}^{-6}}}=9,13m=913cm$<br\/>Chu vi c\u1ee7a l\u00f5i s\u1ee9: $C=3,14\\times d=3,14\\times 2,5=7,85cm$<br\/>C\u1ee9 1 v\u00f2ng d\u00e2y c\u00f3 chi\u1ec1u d\u00e0i l\u00e0 7,85cm<br\/>n v\u00f2ng d\u00e2y c\u00f3 chi\u1ec1u d\u00e0i l\u00e0 913cm<br\/>\u21d2S\u1ed1 v\u00f2ng d\u00e2y qu\u1ea5n v\u00e0o l\u00f5i s\u1eaft: $n=\\dfrac{913\\times 1}{7,85}\\approx 116,3$ v\u00f2ng<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2849},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"Khi n\u00f3i v\u1ec1 bi\u1ebfn tr\u1edf trong m\u1ed9t m\u1ea1ch \u0111i\u1ec7n c\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf kh\u00f4ng \u0111\u1ed5i, c\u00e2u ph\u00e1t bi\u1ec3u n\u00e0o sau \u0111\u00e2y l\u00e0 \u0111\u00fang?","select":["A. Bi\u1ebfn tr\u1edf d\u00f9ng \u0111\u1ec3 thay \u0111\u1ed5i chi\u1ec1u d\u00f2ng \u0111i\u1ec7n.","B. Bi\u1ebfn tr\u1edf d\u00f9ng \u0111\u1ec3 thay \u0111\u1ed5i c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n.","C. Bi\u1ebfn tr\u1edf \u0111\u01b0\u1ee3c m\u1eafc song song v\u1edbi m\u1ea1ch \u0111i\u1ec7n.","D. Bi\u1ebfn tr\u1edf d\u00f9ng \u0111\u1ec3 thay \u0111\u1ed5i hi\u1ec7u \u0111i\u1ec7n th\u1ebf."],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":1}]}],"id_ques":2850}],"lesson":{"save":0,"level":2}}