{"segment":[{"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":"\u0110\u1ec3 t\u00ecm hi\u1ec3u s\u1ef1 ph\u1ee5 thu\u1ed9c c\u1ee7a \u0111i\u1ec7n tr\u1edf d\u00e2y d\u1eabn v\u00e0o v\u1eadt li\u1ec7u l\u00e0m d\u00e2y d\u1eabn, c\u1ea7n x\u00e1c \u0111\u1ecbnh v\u00e0 so s\u00e1nh \u0111i\u1ec7n tr\u1edf c\u1ee7a c\u00e1c d\u00e2y d\u1eabn c\u00f3 nh\u1eefng \u0111\u1eb7c \u0111i\u1ec3m n\u00e0o d\u01b0\u1edbi \u0111\u00e2y?","select":["A. C\u00e1c d\u00e2y d\u1eabn c\u00f3 chi\u1ec1u d\u00e0i, ti\u1ebft di\u1ec7n kh\u00e1c nhau v\u00e0 \u0111\u01b0\u1ee3c l\u00e0m t\u1eeb c\u00e1c v\u1eadt li\u1ec7u kh\u00e1c nhau.","B. C\u00e1c d\u00e2y d\u1eabn c\u00f3 chi\u1ec1u d\u00e0i, ti\u1ebft di\u1ec7n kh\u00e1c nhau v\u00e0 \u0111\u01b0\u1ee3c l\u00e0m t\u1eeb c\u00f9ng m\u1ed9t lo\u1ea1i v\u1eadt li\u1ec7u.","C. C\u00e1c d\u00e2y d\u1eabn c\u00f3 chi\u1ec1u d\u00e0i kh\u00e1c nhau, c\u00f3 ti\u1ebft di\u1ec7n nh\u01b0 nhau v\u00e0 \u0111\u01b0\u1ee3c l\u00e0m t\u1eeb c\u00f9ng m\u1ed9t lo\u1ea1i v\u1eadt li\u1ec7u.","D. C\u00e1c d\u00e2y d\u1eabn c\u00f3 chi\u1ec1u d\u00e0i, ti\u1ebft di\u1ec7n nh\u01b0 nhau v\u00e0 \u0111\u01b0\u1ee3c l\u00e0m t\u1eeb c\u00e1c v\u1eadt li\u1ec7u kh\u00e1c nhau."],"hint":"","explain":"<span class='basic_left'>\u0110\u1ec3 t\u00ecm hi\u1ec3u s\u1ef1 ph\u1ee5 thu\u1ed9c c\u1ee7a \u0111i\u1ec7n tr\u1edf d\u00e2y d\u1eabn v\u00e0o v\u1eadt li\u1ec7u l\u00e0m d\u00e2y d\u1eabn, c\u1ea7n x\u00e1c \u0111\u1ecbnh v\u00e0 so s\u00e1nh \u0111i\u1ec7n tr\u1edf c\u1ee7a c\u00e1c d\u00e2y d\u1eabn c\u00f3 nh\u1eefng \u0111\u1eb7c \u0111i\u1ec3m: C\u00e1c d\u00e2y d\u1eabn c\u00f3 chi\u1ec1u d\u00e0i, ti\u1ebft di\u1ec7n nh\u01b0 nhau v\u00e0 \u0111\u01b0\u1ee3c l\u00e0m t\u1eeb c\u00e1c v\u1eadt li\u1ec7u kh\u00e1c nhau.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":1}]}],"id_ques":2811},{"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":"Bi\u1ebft \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a nh\u00f4m l\u00e0 $2,8\\times {{10}^{-8}}\\Omega m$, c\u1ee7a v\u00f4nfram l\u00e0 $5,5\\times {{10}^{-8}}\\Omega m$, c\u1ee7a s\u1eaft l\u00e0 $12,0\\times {{10}^{-8}}\\Omega m$. S\u1ef1 so s\u00e1nh n\u00e0o d\u01b0\u1edbi \u0111\u00e2y l\u00e0 \u0111\u00fang?","select":["A. S\u1eaft d\u1eabn \u0111i\u1ec7n t\u1ed1t h\u01a1n vonfram v\u00e0 vonfram d\u1eabn \u0111i\u1ec7n t\u1ed1t h\u01a1n nh\u00f4m.","B. Vonfram d\u1eabn \u0111i\u1ec7n t\u1ed1t h\u01a1n s\u1eaft v\u00e0 s\u1eaft d\u1eabn \u0111i\u1ec7n t\u1ed1t h\u01a1n nh\u00f4m.","C. Nh\u00f4m d\u1eabn \u0111i\u1ec7n t\u1ed1t h\u01a1n vonfram v\u00e0 vonfram d\u1eabn \u0111i\u1ec7n t\u1ed1t h\u01a1n s\u1eaft.","D. Nh\u00f4m d\u1eabn \u0111i\u1ec7n t\u1ed1t h\u01a1n s\u1eaft v\u00e0 s\u1eaft d\u1eabn \u0111i\u1ec7n t\u1ed1t h\u01a1n vonfram."],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a v\u1eadt li\u1ec7u c\u00e0ng nh\u1ecf th\u00ec v\u1eadt li\u1ec7u \u0111\u00f3 d\u1eabn \u0111i\u1ec7n c\u00e0ng t\u1ed1t.N\u00ean:Nh\u00f4m d\u1eabn \u0111i\u1ec7n t\u1ed1t h\u01a1n vonfram v\u00e0 vonfram d\u1eabn \u0111i\u1ec7n t\u1ed1t h\u01a1n s\u1eaft.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":1}]}],"id_ques":2812},{"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":"\u1ede c\u00e1c nh\u00e0 cao t\u1ea7ng ng\u01b0\u1eddi ta th\u01b0\u1eddng l\u1eafp c\u1ed9t thu l\u00f4i \u0111\u1ec3 ch\u1ed1ng s\u00e9t. D\u00e2y n\u1ed1i \u0111\u1ea7u c\u1ed9t thu l\u00f4i xu\u1ed1ng \u0111\u1ea5t l\u00e0 d\u00e2y s\u1eaft, c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t l\u00e0 $12,0\\times {{10}^{-8}}\\Omega m$. T\u00ednh \u0111i\u1ec7n tr\u1edf c\u1ee7a m\u1ed9t d\u00e2y d\u1eabn b\u1eb1ng s\u1eaft n\u00e0y n\u1ebfu n\u00f3 d\u00e0i 40m v\u00e0 c\u00f3 \u0111\u01b0\u1eddng k\u00ednh ti\u1ebft di\u1ec7n l\u00e0 8mm.","select":["A. 0,0955\u2126","B. 9\u2126 ","C. 4\u2126 ","D. 8,55\u2126"],"hint":"","explain":"<span class='basic_left'>Ti\u1ebft di\u1ec7n c\u1ee7a d\u00e2y s\u1eaft :<br \/><br \/> $S =\\frac{\u03c0.d^{2}}{4} =\\frac{3.14.8^{2}}{4}= 50,24mm^2 =50,24.10^{-6}m^2$ <br \/> <br \/> \u0110i\u1ec7n tr\u1edf c\u1ee7a m\u1ed9t d\u00e2y d\u1eabn b\u1eb1ng s\u1eaft l\u00e0: $R = \\frac{\\rho.l}{S} = \\frac{12.10^{-8}.40}{50,24.10^{-6}} =0,0955\\Omega$<br\/> <br \/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2813},{"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 s\u1ee3i d\u00e2y \u0111\u1ed3ng d\u00e0i 100m c\u00f3 ti\u1ebft di\u1ec7n l\u00e0 $2m{{m}^{2}}$. T\u00ednh \u0111i\u1ec7n tr\u1edf c\u1ee7a s\u1ee3i d\u00e2y \u0111\u1ed3ng n\u00e0y, bi\u1ebft \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a \u0111\u1ed3ng l\u00e0 $1,7\\times {{10}^{-8}}\\Omega m$.","select":["A. 0,45\u03a9 ","B. 0,2\u03a9 ","C. 0,85 \u03a9 ","D. 0,34\u03a9"],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf c\u1ee7a s\u1ee3i d\u00e2y \u0111\u1ed3ng l\u00e0: $R=\\rho \\times \\dfrac{l}{S}=1,7\\times {{10}^{-8}}\\times \\dfrac{100}{2\\times {{10}^{-6}}}=0,85\\Omega $<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2814},{"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 cu\u1ed9n d\u00e2y d\u1eabn b\u1eb1ng \u0111\u1ed3ng v\u1edbi kh\u1ed1i l\u01b0\u1ee3ng c\u1ee7a d\u00e2y d\u1eabn l\u00e0 0,5kg v\u00e0 d\u00e2y d\u1eabn c\u00f3 ti\u1ebft di\u1ec7n $1m{{m}^{2}}$. T\u00ednh chi\u1ec1u d\u00e0i d\u00e2y d\u1eabn, bi\u1ebft kh\u1ed1i l\u01b0\u1ee3ng ri\u00eang c\u1ee7a \u0111\u1ed3ng l\u00e0 $8900\\dfrac{kg}{{{m}^{3}}}$. T\u00ednh \u0111i\u1ec7n tr\u1edf c\u1ee7a cu\u1ed9n d\u00e2y n\u00e0y, bi\u1ebft \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a \u0111\u1ed3ng l\u00e0 $1,7\\times {{10}^{-8}}\\Omega m$. ","select":["A. 56,8m; 2\u03a9","B. 50m; 1\u03a9","C. 56,18 m; 1\u03a9","D. 1m; 56,18\u03a9"],"hint":"","explain":"<span class='basic_left'>Chi\u1ec1u d\u00e0i c\u1ee7a d\u00e2y d\u1eabn l\u00e0: $l=\\dfrac{V}{S}=\\dfrac{m}{D\\times S}=\\dfrac{0,5}{8900\\times {{10}^{-6}}}\\approx 56,18m$<br\/>\u0110i\u1ec7n tr\u1edf cu\u1ed9n d\u00e2y l\u00e0: $R=\\rho \\times \\dfrac{l}{S}=1,7\\times {{10}^{-8}}\\times \\dfrac{56,18}{{{10}^{-6}}}=0,955\\Omega \\approx 1\\Omega $<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2815},{"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":"Trong c\u00e1c kim lo\u1ea1i \u0111\u1ed3ng, nh\u00f4m, s\u1eaft v\u00e0 b\u1ea1c, kim lo\u1ea1i n\u00e0o d\u1eabn \u0111i\u1ec7n t\u1ed1t nh\u1ea5t? ","select":["A. S\u1eaft ","B. Nh\u00f4m ","C. B\u1ea1c ","D. \u0110\u1ed3ng"],"hint":"","explain":"<span class='basic_left'>V\u00ec b\u1ea1c c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t nh\u1ecf nh\u1ea5t.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2816},{"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":"Trong s\u1ed1 c\u00e1c kim lo\u1ea1i l\u00e0 \u0111\u1ed3ng, s\u1eaft, nh\u00f4m v\u00e0 vonfram, kim lo\u1ea1i n\u00e0o d\u1eabn \u0111i\u1ec7n k\u00e9m nh\u1ea5t? ","select":["A. Vonfram","B. S\u1eaft","C. Nh\u00f4m","D. \u0110\u1ed3ng"],"hint":"","explain":"<span class='basic_left'>V\u00ec s\u1eaft c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t l\u1edbn nh\u1ea5t.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2817},{"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 $1,1\\times {{10}^{-6}}\\Omega m$\u0111\u1ec3 l\u00e0m d\u00e2y nung cho m\u1ed9t b\u1ebfp \u0111i\u1ec7n. \u0110i\u1ec7n tr\u1edf c\u1ee7a d\u00e2y nung n\u00e0y \u1edf nhi\u1ec7t \u0111\u1ed9 b\u00ecnh th\u01b0\u1eddng l\u00e0 4,5\u2126 v\u00e0 c\u00f3 chi\u1ec1u d\u00e0i t\u1ed5ng c\u1ed9ng l\u00e0 0,8m. H\u1ecfi d\u00e2y nung n\u00e0y ph\u1ea3i c\u00f3 \u0111\u01b0\u1eddng k\u00ednh ti\u1ebft di\u1ec7n l\u00e0 bao nhi\u00eau?","select":["A. 0,5 cm","B. 0,5 m","C. 0,05 mm","D. 0,5 mm"],"hint":"","explain":"<span class='basic_left'>Ti\u1ebft di\u1ec7n c\u1ee7a d\u00e2y nicrom: $S=\\rho \\times \\dfrac{l}{R}=\\dfrac{1,1\\times {{10}^{-6}}\\times 0,8}{4,5}=0,2\\times {{10}^{-6}}\\left( {{m}^{2}} \\right)$<br\/>\u0110\u01b0\u1eddng k\u00ednh c\u1ee7a d\u00e2y nung: $S=\\dfrac{3,14\\times {{d}^{2}}}{4}\\Rightarrow d=\\sqrt{\\dfrac{4S}{3,14}}=\\sqrt{\\dfrac{4\\times 0,2\\times {{10}^{-6}}}{3,14}}=0,25\\times {{10}^{-3}}{{m}^{2}}\\Rightarrow d=0,5mm$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2818},{"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":"C\u00f3 ba d\u00e2y d\u1eabn v\u1edbi chi\u1ec1u d\u00e0i v\u00e0 ti\u1ebft di\u1ec7n nh\u01b0 nhau. D\u00e2y th\u1ee9 nh\u1ea5t b\u1eb1ng b\u1ea1c c\u00f3 \u0111i\u1ec7n tr\u1edf ${{R}_{1}}$, d\u00e2y th\u1ee9 hai b\u1eb1ng \u0111\u1ed3ng c\u00f3 \u0111i\u1ec7n tr\u1edf ${{R}_{2}}$ v\u00e0 d\u00e2y th\u1ee9 ba b\u1eb1ng nh\u00f4m c\u00f3 \u0111i\u1ec7n tr\u1edf ${{R}_{3}}$. Khi so s\u00e1nh c\u00e1c \u0111i\u1ec7n tr\u1edf n\u00e0y, ta c\u00f3: ","select":["A. ${{R}_{1}}>{{R}_{2}}>{{R}_{3}}$","B. ${{R}_{1}}>{{R}_{3}}>{{R}_{2}}$","C. ${{R}_{2}}>{{R}_{1}}>{{R}_{3}}$","D. ${{R}_{3}}>{{R}_{2}}>{{R}_{1}}$"],"hint":"","explain":"<span class='basic_left'>Khi so s\u00e1nh c\u00e1c \u0111i\u1ec7n tr\u1edf c\u00f3 chi\u1ec1u d\u00e0i v\u00e0 ti\u1ebft di\u1ec7n nh\u01b0 nhau, \u0111i\u1ec7n tr\u1edf n\u00e0o l\u00e0m b\u1eb1ng ch\u1ea5t li\u1ec7u c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t l\u1edbn h\u01a1n th\u00ec l\u1edbn h\u01a1n. Theo th\u1ee9 t\u1ef1 t\u0103ng d\u1ea7n v\u1ec1 kh\u1ea3 n\u0103ng d\u1eabn \u0111i\u1ec7n ta c\u00f3: Nh\u00f4m<\u0110\u1ed3ng<B\u1ea1c. V\u1eady th\u1ee9 t\u1ef1 \u0111i\u1ec7n tr\u1edf \u0111\u00fang l\u00e0 D.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2819},{"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 cu\u1ed9n d\u00e2y \u0111i\u1ec7n tr\u1edf c\u00f3 tr\u1ecb s\u1ed1 l\u00e0 10\u2126 \u0111\u01b0\u1ee3c qu\u1ea5n b\u1eb1ng d\u00e2y Nik\u00ealin c\u00f3 ti\u1ebft di\u1ec7n l\u00e0 $0,1m{{m}^{2}}$ v\u00e0 c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t l\u00e0 $0,4\\times {{10}^{-6}}\\Omega m$. T\u00ednh chi\u1ec1u d\u00e0i c\u1ee7a d\u00e2y Nik\u00ealin d\u00f9ng \u0111\u1ec3 qu\u1ea5n cu\u1ed9n d\u00e2y \u0111i\u1ec7n tr\u1edf n\u00e0y?","select":["A. 1,0m","B. 2,0m","C. 2,5m","D. 1,5m"],"hint":"","explain":"<span class='basic_left'>Chi\u1ec1u d\u00e0i c\u1ee7a d\u00e2y nikelin: $l=\\dfrac{R\\times S}{\\rho }=\\dfrac{10\\times 0,1\\times {{10}^{-6}}}{0,4\\times {{10}^{-6}}}=2,5m$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2820},{"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":"D\u00e2y d\u1eabn b\u1eb1ng \u0111\u1ed3ng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng r\u1ea5t ph\u1ed5 bi\u1ebfn. \u0110i\u1ec1u n\u00e0y kh\u00f4ng ph\u1ea3i v\u00ec l\u00ed do n\u00e0o d\u01b0\u1edbi \u0111\u00e2y","select":["A. D\u00e2y b\u1eb1ng \u0111\u1ed3ng ch\u1ecbu \u0111\u01b0\u1ee3c l\u1ef1c k\u00e9o c\u0103ng t\u1ed1t h\u01a1n d\u00e2y b\u1eb1ng nh\u00f4m.","B. \u0110\u1ed3ng l\u00e0 kim lo\u1ea1i c\u00f3 tr\u1ecdng l\u01b0\u1ee3ng ri\u00eang nh\u1ecf h\u01a1n nh\u00f4m.","C. \u0110\u1ed3ng l\u00e0 ch\u1ea5t d\u1eabn \u0111i\u1ec7n v\u00e0o lo\u1ea1i t\u1ed1t nh\u1ea5t trong s\u1ed1 c\u00e1c kim lo\u1ea1i v\u00e0 t\u1ed1t h\u01a1n nh\u00f4m.","D. \u0110\u1ed3ng l\u00e0 v\u1eadt li\u1ec7u kh\u00f4ng qu\u00e1 \u0111\u1eaft so v\u1edbi nh\u00f4m v\u00e0 d\u1ec5 ki\u1ebfm."],"hint":"","explain":"<span class='basic_left'>D\u00e2y d\u1eabn b\u1eb1ng \u0111\u1ed3ng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng r\u1ea5t ph\u1ed5 bi\u1ebfn v\u00ec \u0111\u1ed3ng ch\u1ecbu \u0111\u01b0\u1ee3c l\u1ef1c k\u00e9o c\u0103ng t\u1ed1t h\u01a1n d\u00e2y b\u1eb1ng nh\u00f4m, l\u00e0 ch\u1ea5t d\u1eabn \u0111i\u1ec7n v\u00e0o lo\u1ea1i t\u1ed1t nh\u1ea5t trong s\u1ed1 c\u00e1c kim lo\u1ea1i v\u00e0 t\u1ed1t h\u01a1n nh\u00f4m, l\u00e0 v\u1eadt li\u1ec7u kh\u00f4ng qu\u00e1 \u0111\u1eaft so v\u1edbi nh\u00f4m v\u00e0 d\u1ec5 ki\u1ebfm.<br\/>\u00dd B sai v\u00ec: \u0110\u1ed3ng l\u00e0 kim lo\u1ea1i c\u00f3 tr\u1ecdng l\u01b0\u1ee3ng ri\u00eang l\u1edbn h\u01a1n nh\u00f4m. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":1}]}],"id_ques":2821},{"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":"H\u1ec7 th\u1ee9c n\u00e0o d\u01b0\u1edbi \u0111\u00e2y bi\u1ec3u th\u1ecb m\u1ed1i quan h\u1ec7 gi\u1eefa \u0111i\u1ec7n tr\u1edf R c\u1ee7a d\u00e2y d\u1eabn v\u1edbi chi\u1ec1u d\u00e0i l, ti\u1ebft di\u1ec7n S c\u1ee7a d\u00e2y d\u1eabn v\u00e0 v\u1edbi \u0111i\u1ec7n tr\u1edf su\u1ea5t \u03c1 c\u1ee7a v\u1eadt li\u1ec7u l\u00e0m d\u00e2y d\u1eabn? ","select":["A. $R=\\dfrac{S}{l}\\times \\rho $","B. $R=\\dfrac{l}{S\\times \\rho }$","C. $R=\\dfrac{l\\times S}{\\rho }$","D. $R=\\rho \\times \\dfrac{l}{S}$"],"hint":"","explain":"<span class='basic_left'><br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2822},{"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 cu\u1ed9n d\u00e2y \u0111i\u1ec7n tr\u1edf c\u00f3 tr\u1ecb s\u1ed1 l\u00e0 10\u2126 \u0111\u01b0\u1ee3c qu\u1ea5n b\u1eb1ng d\u00e2y Nik\u00ealin c\u00f3 ti\u1ebft di\u1ec7n l\u00e0 $0,1m{{m}^{2}}$ v\u00e0 c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t l\u00e0 $0,4\\times {{10}^{-6}}\\Omega m$. M\u1eafc cu\u1ed9n d\u00e2y \u0111i\u1ec7n tr\u1edf n\u00f3i tr\u00ean n\u1ed1i ti\u1ebfp v\u1edbi m\u1ed9t \u0111i\u1ec7n tr\u1edf c\u00f3 tr\u1ecb s\u1ed1 l\u00e0 5\u03a9 v\u00e0 \u0111\u1eb7t v\u00e0o hai \u0111\u1ea7u \u0111o\u1ea1n m\u1ea1ch n\u1ed1i ti\u1ebfp n\u00e0y m\u1ed9t hi\u1ec7u \u0111i\u1ec7n th\u1ebf l\u00e0 3V. T\u00ednh hi\u1ec7u \u0111i\u1ec7n th\u1ebf gi\u1eefa hai \u0111\u1ea7u cu\u1ed9n d\u00e2y \u0111i\u1ec7n tr\u1edf.","select":["A. 1V","B. 2V","C. 3V","D. 4V"],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf t\u01b0\u01a1ng \u0111\u01b0\u01a1ng v\u00e0 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n trong m\u1ea1ch l\u00e0:<br\/>${{R}_{td}}={{R}_{1}}+{{R}_{2}}=10+5=15\\Omega $<br\/>$\\Rightarrow I=\\dfrac{U}{{{R}_{td}}}=\\dfrac{3}{15}=0,2A={{I}_{1}}={{I}_{2}}$<br\/>Hi\u1ec7u \u0111i\u1ec7n th\u1ebf gi\u1eefa hai \u0111\u1ea7u cu\u1ed9n d\u00e2y: ${{U}_{cd}}=I\\times {{R}_{1}}=0,2\\times 10=2V$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2823},{"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":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang. \u0110i\u1ec7n tr\u1edf d\u00e2y d\u1eabn:","select":["A. T\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi chi\u1ec1u d\u00e0i.","B. T\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi ti\u1ebft di\u1ec7n.","C. Kh\u00f4ng ph\u1ee5 thu\u1ed9c v\u00e0o v\u1eadt li\u1ec7u l\u00e0m d\u00e2y.","D. T\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi chi\u1ec1u d\u00e0i, t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi ti\u1ebft di\u1ec7n c\u1ee7a d\u00e2y v\u00e0 ph\u1ee5 thu\u1ed9c v\u00e0 v\u1eadt li\u1ec7u l\u00e0m d\u00e2y."],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf d\u00e2y d\u1eabn t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi chi\u1ec1u d\u00e0i, t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi ti\u1ebft di\u1ec7n c\u1ee7a d\u00e2y v\u00e0 ph\u1ee5 thu\u1ed9c v\u00e0 v\u1eadt li\u1ec7u l\u00e0m d\u00e2y.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2824},{"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":"Trong s\u1ed1 c\u00e1c v\u1eadt li\u1ec7u \u0111\u1ed3ng, nh\u00f4m, s\u1eaft v\u00e0 nicrom, v\u1eadt \u0111i\u1ec7n n\u00e0o d\u1eabn \u0111i\u1ec7n k\u00e9m nh\u1ea5t?","select":["A. \u0110\u1ed3ng","B. Nh\u00f4m","C. S\u1eaft","D. Nicrom"],"hint":"","explain":"<span class='basic_left'>V\u00ec nicrom c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t 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":2825},{"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":"Trong c\u00e1c kim lo\u1ea1i \u0111\u1ed3ng, vonfram, nikelin, manganin, kim lo\u1ea1i n\u00e0o d\u1eabn \u0111i\u1ec7n t\u1ed1t nh\u1ea5t? ","select":["A. Manganin","B. Nikelin","C. Vonfram","D. \u0110\u1ed3ng"],"hint":"","explain":"<span class='basic_left'>V\u00ec \u0111\u1ed3ng c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t nh\u1ecf nh\u1ea5t.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2826},{"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 d\u00e2y d\u1eabn b\u1eb1ng nicrom d\u00e0i 15m, ti\u1ebft di\u1ec7n $0,3m{{m}^{2}}$\u0111\u01b0\u1ee3c m\u1eafc v\u00e0o hai \u0111i\u1ec3m c\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf 220V. Bi\u1ebft \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a nicrom l\u00e0 $1,1\\times {{10}^{-6}}\\Omega m$. C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua d\u00e2y d\u1eabn c\u00f3 gi\u00e1 tr\u1ecb l\u00e0:","select":["A. I = 2A","B. I = 4A","C. I = 6A","D. I = 8A"],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf d\u00e2y nicrom: $R=\\rho \\times \\dfrac{l}{S}=\\dfrac{1,1\\times {{10}^{-6}}\\times 15}{0,3\\times {{10}^{-6}}}=55\\Omega $<br\/>C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n: $I=\\dfrac{U}{R}=\\dfrac{220}{55}=4A$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2827},{"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 d\u00e2y d\u1eabn b\u1eb1ng \u0111\u1ed3ng v\u00e0 m\u1ed9t d\u00e2y d\u1eabn b\u1eb1ng nh\u00f4m c\u00f3 c\u00f9ng chi\u1ec1u d\u00e0i, c\u00f9ng ti\u1ebft di\u1ec7n. So s\u00e1nh \u0111i\u1ec7n tr\u1edf c\u1ee7a hai d\u00e2y?","select":["A. ${{R}_{Cu}}={{R}_{Al}}$","B. ${{R}_{Cu}}>{{R}_{Al}}$","C. ${{R}_{Cu}}<{{R}_{Al}}$","D. ${{R}_{Cu}}=2{{R}_{Al}}$"],"hint":"","explain":"<span class='basic_left'>Do \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a \u0111\u1ed3ng nh\u1ecf h\u01a1n n\u00ean \u0111i\u1ec7n tr\u1edf d\u00e2y \u0111\u1ed3ng nh\u1ecf h\u01a1n \u0111i\u1ec7n tr\u1edf d\u00e2y nh\u00f4m.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2828},{"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 d\u00e2y d\u1eabn b\u1eb1ng constantan d\u00e0i 20m, ti\u1ebft di\u1ec7n $0,4m{{m}^{2}}$\u0111\u01b0\u1ee3c m\u1eafc v\u00e0o hai \u0111i\u1ec3m c\u00f3 hi\u1ec7u \u0111i\u1ec7n th\u1ebf 220V. Bi\u1ebft \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a constantan l\u00e0 $0,5\\times {{10}^{-6}}\\Omega m$. C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua d\u00e2y d\u1eabn c\u00f3 gi\u00e1 tr\u1ecb l\u00e0:","select":["A. I = 2,2A","B. I = 4,4A","C. I = 6,6A","D. I = 8,8A"],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf d\u00e2y nicrom: $R=\\rho \\times \\dfrac{l}{S}=\\dfrac{0,5\\times {{10}^{-6}}\\times 20}{0,4\\times {{10}^{-6}}}=25\\Omega $<br\/>C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n: $I=\\dfrac{U}{R}=\\dfrac{220}{25}=8,8A$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2829},{"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":"\u1ede c\u00e1c nh\u00e0 cao t\u1ea7ng ng\u01b0\u1eddi ta th\u01b0\u1eddng l\u1eafp c\u1ed9t thu l\u00f4i \u0111\u1ec3 ch\u1ed1ng s\u00e9t. D\u00e2y n\u1ed1i \u0111\u1ea7u c\u1ed9t thu l\u00f4i xu\u1ed1ng \u0111\u1ea5t l\u00e0 d\u00e2y s\u1eaft, c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t l\u00e0 $12\\times {{10}^{-8}}\\Omega m$ . T\u00ednh \u0111i\u1ec7n tr\u1edf c\u1ee7a m\u1ed9t d\u00e2y d\u1eabn b\u1eb1ng s\u1eaft n\u00e0y n\u1ebfu n\u00f3 d\u00e0i 40m v\u00e0 c\u00f3 \u0111\u01b0\u1eddng k\u00ednh ti\u1ebft di\u1ec7n l\u00e0 8mm?","select":["A. $8,5\\Omega $ ","B. $8,55\\Omega $ ","C. $9,55\\Omega $ ","D. $9,5\\Omega $ "],"hint":"","explain":"<span class='basic_left'>Ti\u1ebft di\u1ec7n c\u1ee7a d\u00e2y s\u1eaft :<br\/>$S=\\dfrac{\\pi {{d}^{2}}}{4}=\\dfrac{3,14\\times {{8}^{2}}}{4}=50,24m{{m}^{2}}=50,24\\times {{10}^{-6}}{{m}^{2}}$<br\/> \u0110i\u1ec7n tr\u1edf c\u1ee7a d\u00e2y s\u1eaft:<br\/>$R=\\rho \\dfrac{l}{S}=12\\times {{10}^{-8}}\\times \\dfrac{40}{50,24\\times {{10}^{-6}}}=9,55\\Omega $ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2830}],"lesson":{"save":0,"level":2}}