{"segment":[{"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 \u0111o\u1ea1n m\u1ea1ch g\u1ed3m hai d\u00e2y d\u1eabn m\u1eafc n\u1ed1i ti\u1ebfp, m\u1ed9t d\u00e2y b\u1eb1ng nik\u00ealin d\u00e0i 1m c\u00f3 ti\u1ebft di\u1ec7n $1m{{m}^{2}}$ v\u00e0 d\u00e2y kia b\u1eb1ng s\u1eaft d\u00e0i 2m c\u00f3 ti\u1ebft di\u1ec7n $0,5m{{m}^{2}}$. Khi cho d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua \u0111o\u1ea1n m\u1ea1ch n\u00e0y trong c\u00f9ng m\u1ed9t th\u1eddi gian th\u00ec d\u00e2y n\u00e0o t\u1ecfa ra nhi\u1ec1u nhi\u1ec7t l\u01b0\u1ee3ng h\u01a1n? Bi\u1ebft \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a nik\u00ealin l\u00e0 $0,40\\times {{10}^{-6}}\\Omega .m$ v\u00e0 \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a s\u1eaft l\u00e0 $12,0\\times {{10}^{-8}}\\Omega .m$.","select":["A. D\u00e2y nik\u00ealin t\u1ecfa ra nhi\u1ec1u nhi\u1ec7t l\u01b0\u1ee3ng h\u01a1n.","B. D\u00e2y s\u1eaft t\u1ecfa ra nhi\u1ec1u nhi\u1ec7t l\u01b0\u1ee3ng h\u01a1n.","C. Hai d\u00e2y t\u1ecfa nhi\u1ec7t l\u01b0\u1ee3ng b\u1eb1ng nhau.","D. C\u1ea3 ba \u0111\u00e1p \u00e1n \u0111\u1ec1u sai."],"hint":"","explain":"<span class='basic_left'>D\u00e2y s\u1eaft t\u1ecfa ra nhi\u1ec1u nhi\u1ec7t l\u01b0\u1ee3ng h\u01a1n. Ta c\u00f3:<br\/>\u0110i\u1ec7n tr\u1edf c\u1ee7a d\u00e2y Nik\u00ealin l\u00e0:<br\/>${{R}_{1}}=\\dfrac{{{\\rho }_{1}}\\times {{l}_{1}}}{{{S}_{1}}}=\\dfrac{0,40\\times {{10}^{-6}}\\times 1}{{{10}^{-6}}}=0,4\\Omega $<br\/> \u0110i\u1ec7n tr\u1edf c\u1ee7a d\u00e2y s\u1eaft l\u00e0:<br\/>${{R}_{2}}=\\dfrac{{{\\rho }_{2}}\\times {{l}_{2}}}{{{S}_{2}}}=\\dfrac{12,0\\times {{10}^{-8}}\\times 2}{0,5\\times {{10}^{-6}}}=0,48\\Omega $<br\/>$R_1$ v\u00e0 $R_2$ m\u1eafc n\u1ed1i ti\u1ebfp n\u00ean d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua ch\u00fang c\u00f3 c\u00f9ng c\u01b0\u1eddng \u0111\u1ed9 I. <br\/>K\u00ed hi\u1ec7u nhi\u1ec7t l\u01b0\u1ee3ng t\u1ecfa ra \u1edf c\u00e1c \u0111i\u1ec7n tr\u1edf n\u00e0y t\u01b0\u01a1ng \u1ee9ng l\u00e0 $Q_1$ v\u00e0 $Q_2$.<br\/>Ta c\u00f3: ${{I}^{2}}t=\\dfrac{{{Q}_{1}}}{{{R}_{1}}}=\\dfrac{{{Q}_{2}}}{{{R}_{2}}}$ <br\/>Suy ra: $\\dfrac{{{Q}_{1}}}{{{Q}_{2}}}=\\dfrac{{{R}_{1}}}{{{R}_{2}}}$ <br\/>M\u00e0 $R_2$>$R_1$ , N\u00ean ta c\u00f3 $Q_2$<$Q_1$.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2991},{"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\u1ecbnh lu\u1eadt Jun \u2013 Lenx\u01a1 cho bi\u1ebft \u0111i\u1ec7n n\u0103ng bi\u1ebfn \u0111\u1ed5i th\u00e0nh:","select":["A. C\u01a1 n\u0103ng.","B. N\u0103ng l\u01b0\u1ee3ng \u00e1nh s\u00e1ng.","C. H\u00f3a n\u0103ng.","D. Nhi\u1ec7t n\u0103ng."],"hint":"","explain":"<span class='basic_left'>Theo \u0111\u1ecbnh lu\u1eadt jun- Len x\u01a1: Nhi\u1ec7t l\u01b0\u1ee3ng t\u1ecfa ra \u1edf d\u00e2y d\u1eabn khi c\u00f3 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua t\u1ef7 l\u1ec7 thu\u1eadn v\u1edbi b\u00ecnh ph\u01b0\u01a1ng c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n, v\u1edbi \u0111i\u1ec7n tr\u1edf c\u1ee7a d\u00e2y d\u1eabn v\u00e0 th\u1eddi gian d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua. Hay \u0111i\u1ec7n n\u0103ng bi\u1ebfn \u0111\u1ed5i th\u00e0nh nhi\u1ec7t n\u0103ng.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2992},{"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":"Khi cho d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua \u0111o\u1ea1n m\u1ea1ch g\u1ed3m $R_1$ v\u00e0 $R_2$ m\u1eafc n\u1ed1i ti\u1ebfp th\u00ec nhi\u1ec7t l\u01b0\u1ee3ng t\u1ecfa ra \u1edf m\u1ed7i \u0111i\u1ec7n tr\u1edf c\u00f3 m\u1ed1i quan h\u1ec7 v\u1edbi c\u00e1c \u0111i\u1ec7n tr\u1edf \u0111\u00f3 nh\u01b0 th\u1ebf n\u00e0o? ","select":["A. $\\dfrac{{{Q}_{1}}}{{{Q}_{2}}}=\\dfrac{{{R}_{1}}}{{{R}_{2}}}$.","B. $\\dfrac{{{Q}_{2}}}{{{Q}_{1}}}=\\dfrac{{{R}_{1}}}{{{R}_{2}}}$.","C. $\\dfrac{{{Q}_{1}}}{{{Q}_{2}}}<\\dfrac{{{R}_{1}}}{{{R}_{2}}}$.","D. $\\dfrac{{{Q}_{1}}}{{{Q}_{2}}}>\\dfrac{{{R}_{1}}}{{{R}_{2}}}$."],"hint":"","explain":"<span class='basic_left'>$R_1$ v\u00e0 $R_2$ m\u1eafc n\u1ed1i ti\u1ebfp n\u00ean d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua ch\u00fang c\u00f3 c\u00f9ng c\u01b0\u1eddng \u0111\u1ed9 I. K\u00ed hi\u1ec7u nhi\u1ec7t l\u01b0\u1ee3ng t\u1ecfa ra \u1edf c\u00e1c \u0111i\u1ec7n tr\u1edf n\u00e0y t\u01b0\u01a1ng \u1ee9ng l\u00e0 $Q_1$ v\u00e0 $Q_2$.<br\/>Ta c\u00f3: ${{I}^{2}}t=\\dfrac{{{Q}_{1}}}{{{R}_{1}}}=\\dfrac{{{Q}_{2}}}{{{R}_{2}}}$<br\/>Suy ra: $\\dfrac{{{Q}_{1}}}{{{Q}_{2}}}=\\dfrac{{{R}_{1}}}{{{R}_{2}}}$.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2993},{"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":"Th\u1eddi gian \u0111un s\u00f4i 1,5 l\u00edt n\u01b0\u1edbc c\u1ee7a m\u1ed9t \u1ea5m \u0111i\u1ec7n l\u00e0 10 ph\u00fat. Hi\u1ec7u \u0111i\u1ec7n th\u1ebf gi\u1eefa hai \u0111\u1ea7u d\u00e2y nung c\u1ee7a \u1ea5m l\u00e0 220V. T\u00ednh \u0111i\u1ec7n tr\u1edf c\u1ee7a d\u00e2y nung n\u00e0y, bi\u1ebft r\u1eb1ng n\u1ebfu k\u1ec3 c\u1ea3 nhi\u1ec7t l\u01b0\u1ee3ng hao ph\u00ed \u0111\u1ec3 \u0111un s\u00f4i 1 l\u00edt n\u01b0\u1edbc th\u00ec c\u1ea7n nhi\u1ec7t l\u01b0\u1ee3ng l\u00e0 420000J.","select":["A. 24\u2126","B. 23\u2126 ","C. 46,1\u2126 ","D. 47\u2126"],"hint":"","explain":"<span class='basic_left'>Nhi\u1ec7t l\u01b0\u1ee3ng c\u1ea7n cung c\u1ea5p \u0111\u1ec3 \u0111un s\u00f4i 1,5 l\u00edt n\u01b0\u1edbc l\u00e0:<br\/>$Q=420000\\times 1,5=630000J$ <br\/>Theo c\u00f4ng th\u1ee9c t\u00ednh nhi\u1ec7t l\u01b0\u1ee3ng t\u1ecfa ra c\u1ee7a \u1ea5m ta c\u00f3:<br\/>$Q={{I}^{2}}Rt$ hay $Q=\\dfrac{{{U}^{2}}}{R}t$ <br\/> suy ra: $R=\\dfrac{{{U}^{2}}\\times t}{Q}=\\dfrac{{{220}^{2}}\\times 10\\times 60}{630000}=46,1\\Omega $ .<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2994},{"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":"M\u1ed9t b\u1ebfp \u0111i\u1ec7n \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng v\u1edbi hi\u1ec7u \u0111i\u1ec7n th\u1ebf 220V th\u00ec d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua b\u1ebfp \u0111i\u1ec7n c\u00f3 c\u01b0\u1eddng \u0111\u1ed9 3A. D\u00f9ng b\u1ebfp n\u00e0y \u0111un s\u00f4i \u0111\u01b0\u1ee3c 2 l\u00edt n\u01b0\u1edbc t\u1eeb nhi\u1ec7t \u0111\u1ed9 ban \u0111\u1ea7u $20{}^\\circ C$ trong th\u1eddi gian 20 ph\u00fat. T\u00ednh hi\u1ec7u su\u1ea5t c\u1ee7a b\u1ebfp \u0111i\u1ec7n, bi\u1ebft nhi\u1ec7t dung ri\u00eang c\u1ee7a n\u01b0\u1edbc l\u00e0 c=4200J\/kg.K.","select":["A. 84,8 %","B. 40% ","C. 42,5% ","D. 21,25%"],"hint":"","explain":"<span class='basic_left'>Nhi\u1ec7t l\u01b0\u1ee3ng m\u00e0 b\u1ebfp t\u1ecfa ra trong 20 ph\u00fat l\u00e0:<br\/>${{Q}_{tp}}=UIt=220\\times 3\\times 20\\times 60=792000J$ <br\/>Nhi\u1ec7t l\u01b0\u1ee3ng c\u1ea7n cung c\u1ea5p \u0111\u1ec3 \u0111un s\u00f4i l\u01b0\u1ee3ng n\u01b0\u1edbc n\u00e0y l\u00e0:<br\/>${{Q}_{1}}=cm({{t}_{2}}^{0}-{{t}_{1}}^{0})=4200\\times 2\\times 80=672000J$ <br\/>Hi\u1ec7u su\u1ea5t c\u1ee7a b\u1ebfp l\u00e0:<br\/>$H=\\dfrac{{{Q}_{1}}}{{{Q}_{tp}}}=\\dfrac{672000}{792000}=0,848=84,8%$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2995},{"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\u00ecnh n\u00f3ng l\u1ea1nh c\u00f3 ghi 220V-1100W \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng v\u1edbi hi\u1ec7u \u0111i\u1ec7n th\u1ebf 220V. T\u00ednh c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua b\u00ecnh ","select":["A. 3A.","B. 4A.","C. 8A.","D. 5A."],"hint":"","explain":"<span class='basic_left'>C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n qua b\u00ecnh:<br\/>$P=IU\\Rightarrow I=\\dfrac{P}{U}=\\dfrac{1100}{220}=5A$.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2996},{"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\u00ecnh n\u00f3ng l\u1ea1nh c\u00f3 ghi 220V-1100W \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng v\u1edbi hi\u1ec7u \u0111i\u1ec7n th\u1ebf 220V. T\u00ednh th\u1eddi gian \u0111\u1ec3 b\u00ecnh \u0111un s\u00f4i 10 l\u00edt n\u01b0\u1edbc t\u1eeb nhi\u1ec7t \u0111\u1ed9 $20{}^\\circ C$, bi\u1ebft nhi\u1ec7t dung ri\u00eang c\u1ee7a n\u01b0\u1edbc l\u00e0 4200J\/kg.K v\u00e0 nhi\u1ec7t l\u01b0\u1ee3ng b\u1ecb hao ph\u00ed l\u00e0 r\u1ea5t nh\u1ecf.","select":["A. 30 ph\u00fat 45 gi\u00e2y","B. 44 ph\u00fat 20 gi\u00e2y","C. 50 ph\u00fat 55 gi\u00e2y","D. 55 ph\u00fat 55 gi\u00e2y"],"hint":"","explain":"<span class='basic_left'>Th\u1eddi gian \u0111un: $P=\\dfrac{A}{t}\\Rightarrow t=\\dfrac{A}{P}=\\dfrac{m\\times c\\times \\Delta t}{P}=\\dfrac{10\\times 4200\\times 80}{1100}=3054,5s\\approx 50ph55s$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2997},{"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 m\u00f9a \u0111\u00f4ng, m\u1ed9t l\u00f2 s\u01b0\u1edfi \u0111i\u1ec7n c\u00f3 ghi 220V-880W \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng v\u1edbi hi\u1ec7u \u0111i\u1ec7n th\u1ebf 220V trong 4 gi\u1edd m\u1ed7i ng\u00e0y. T\u00ednh nhi\u1ec7t l\u01b0\u1ee3ng m\u00e0 l\u00f2 s\u01b0\u1edfi n\u00e0y t\u1ecfa ra trong m\u1ed7i ng\u00e0y ","select":["A. 4,92 kW.h.","B. 3,52 kW.h.","C. 3,24 kW.h.","D. 2,56 kW.h."],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf c\u1ee7a d\u00e2y nung :<br\/>$P=\\dfrac{{{U}^{2}}}{R}\\Rightarrow R=\\dfrac{{{U}^{2}}}{P}=\\dfrac{{{220}^{2}}}{880}=55\\Omega $ <br\/>C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua n\u00f3:<br\/> $P=UI\\Rightarrow I=\\dfrac{P}{U}=\\dfrac{880}{220}=4A$ <br\/>Nhi\u1ec7t l\u01b0\u1ee3ng t\u1ecfa ra c\u1ee7a l\u00f2 s\u01b0\u1edfi:<br\/>$Q=UIt=220\\times 4\\times 4\\times 3600=12672000J=3,52\\left( kW.h \\right)$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2998},{"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\u1ebfp \u0111i\u1ec7n khi ho\u1ea1t \u0111\u1ed9ng b\u00ecnh th\u01b0\u1eddng c\u00f3 \u0111i\u1ec7n tr\u1edf R = 80\u2126 v\u00e0 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n qua b\u1ebfp khi \u0111\u00f3 l\u00e0 I = 2,5A. T\u00ednh nhi\u1ec7t l\u01b0\u1ee3ng m\u00e0 b\u1ebfp t\u1ecfa ra trong 1s.","select":["A.200J.","B.500J.","C.1000J.","D.1200J."],"hint":"","explain":"<span class='basic_left'>$Q={{I}^{2}}Rt=2,{{5}^{2}}\\times 80\\times 1=500J$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2999},{"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":"M\u1ed9t b\u1ebfp \u0111i\u1ec7n khi ho\u1ea1t \u0111\u1ed9ng b\u00ecnh th\u01b0\u1eddng c\u00f3 \u0111i\u1ec7n tr\u1edf R = 80\u2126 v\u00e0 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n qua b\u1ebfp khi \u0111\u00f3 l\u00e0 I = 2,5A. D\u00f9ng b\u1ebfp \u0111i\u1ec7n \u0111\u1ec3 \u0111un s\u00f4i 1,5l n\u01b0\u1edbc c\u00f3 nhi\u1ec7t \u0111\u1ed9 ban \u0111\u1ea7u l\u00e0 $25{}^\\circ C$ th\u00ec th\u1eddi gian \u0111un n\u01b0\u1edbc l\u00e0 20 ph\u00fat. Coi r\u1eb1ng nhi\u1ec7t l\u01b0\u1ee3ng cung c\u1ea5p \u0111\u1ec3 \u0111un s\u00f4i n\u01b0\u1edbc l\u00e0 c\u00f3 \u00edch, t\u00ednh hi\u1ec7u su\u1ea5t c\u1ee7a b\u1ebfp. Cho bi\u1ebft nhi\u1ec7t dung ri\u00eang c\u1ee7a n\u01b0\u1edbc l\u00e0 c = 4 200J\/kg.K.","select":["A. 78,75%.","B. 87,5%","C. 57,8%.","D. 76,8%."],"hint":"","explain":"<span class='basic_left'>Nhi\u1ec7t l\u01b0\u1ee3ng b\u1ebfp t\u1ecfa ra trong 20 ph\u00fat:<br\/>${{Q}_{tp}}={{I}^{2}}Rt=2,{{5}^{2}}\\times 80\\times 1200=6\\times {{10}^{5}}J$<br\/>Nhi\u1ec7t l\u01b0\u1ee3ng \u0111\u1ec3 \u0111un s\u00f4i n\u01b0\u1edbc l\u00e0:<br\/>${{Q}_{ci}}=mC\\Delta t=1,5\\times (100-25)\\times 4200=472500J$ <br\/>Hi\u1ec7u su\u1ea5t c\u1ee7a b\u1ebfp l\u00e0:<br\/>$H=\\dfrac{{{Q}_{ci}}}{{{Q}_{tp}}}=\\dfrac{472500}{6\\times {{10}^{5}}}=78,75\\% $<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":3000},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"M\u1ed9t b\u1ebfp \u0111i\u1ec7n khi ho\u1ea1t \u0111\u1ed9ng b\u00ecnh th\u01b0\u1eddng c\u00f3 \u0111i\u1ec7n tr\u1edf R = 80\u2126 v\u00e0 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n qua b\u1ebfp khi \u0111\u00f3 l\u00e0 I = 2,5A. M\u1ed7i ng\u00e0y s\u1eed d\u1ee5ng b\u1ebfp \u0111i\u1ec7n n\u00e0y 3 gi\u1edd. T\u00ednh ti\u1ec1n \u0111i\u1ec7n ph\u1ea3i tr\u1ea3 cho vi\u1ec7c s\u1eed d\u1ee5ng b\u1ebfp \u0111i\u1ec7n \u0111\u00f3 trong 30 ng\u00e0y, n\u1ebfu gi\u00e1 1kW.h l\u00e0 700 \u0111\u1ed3ng.","select":["A. 3150 \u0111\u1ed3ng.","B. 31500 \u0111\u1ed3ng.","C. 3150000 \u0111\u1ed3ng.","D. 315000 \u0111\u1ed3ng."],"hint":"","explain":"<span class='basic_left'>L\u01b0\u1ee3ng \u0111i\u1ec7n d\u00f9ng cho b\u1ebfp \u0111i\u1ec7n trong 30 ng\u00e0y l\u00e0:<br\/>$A=30{{I}^{2}}Rt=30\\times 2,{{5}^{2}}\\times 80\\times 3=45000Wh=45kWh$ <br\/>Gi\u00e1 ph\u1ea3i tr\u1ea3 l\u00e0: $45\\times 700=31500$ (\u0111\u1ed3ng)<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":3001},{"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":"M\u1ed9t \u1ea5m \u0111i\u1ec7n c\u00f3 ghi 220V - 1000W \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng v\u1edbi hi\u1ec7u \u0111i\u1ec7n th\u1ebf 220V \u0111\u1ec3 \u0111un s\u00f4i 2l n\u01b0\u1edbc t\u1eeb nhi\u1ec7t \u0111\u1ed9 ban \u0111\u1ea7u $20{}^\\circ C$ . Hi\u1ec7u su\u1ea5t c\u1ee7a \u1ea5m l\u00e0 90%, trong \u0111\u00f3 nhi\u1ec7t l\u01b0\u1ee3ng cung c\u1ea5p \u0111\u1ec3 \u0111un s\u00f4i n\u01b0\u1edbc \u0111\u01b0\u1edbc coi l\u00e0 c\u00f3 \u00edch. T\u00ednh nhi\u1ec7t l\u01b0\u1ee3ng c\u1ea7n cung c\u1ea5p \u0111\u1ec3 \u0111un s\u00f4i l\u01b0\u1ee3ng n\u01b0\u1edbc tr\u00ean, bi\u1ebft nhi\u1ec7t dung ri\u00eang c\u1ee7a n\u01b0\u1edbc l\u00e0 4 200J\/kg.K.","select":["A. 672000J.","B. 720000J.","C. 540000J.","D. 810000J."],"hint":"","explain":"<span class='basic_left'>Nhi\u1ec7t l\u01b0\u1ee3ng m\u00e0 n\u01b0\u1edbc nh\u1eadn v\u00e0o l\u00e0:<br\/> ${{Q}_{ci}}=mC\\Delta t=2\\times 80\\times 4200=672000J$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":3002},{"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 \u1ea5m \u0111i\u1ec7n c\u00f3 ghi 220V - 1000W \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng v\u1edbi hi\u1ec7u \u0111i\u1ec7n th\u1ebf 220V \u0111\u1ec3 \u0111un s\u00f4i 2l n\u01b0\u1edbc t\u1eeb nhi\u1ec7t \u0111\u1ed9 ban \u0111\u1ea7u $20{}^\\circ C$. Hi\u1ec7u su\u1ea5t c\u1ee7a \u1ea5m l\u00e0 90%, trong \u0111\u00f3 nhi\u1ec7t l\u01b0\u1ee3ng cung c\u1ea5p \u0111\u1ec3 \u0111un s\u00f4i n\u01b0\u1edbc \u0111\u01b0\u1edbc coi l\u00e0 c\u00f3 \u00edch. T\u00ednh nhi\u1ec7t l\u01b0\u1ee3ng m\u00e0 \u1ea5m \u0111i\u1ec7n t\u1ecfa ra khi \u0111\u00f3.","select":["A. 672000J.","B. 747000J.","C. 540000J.","D. 810000J."],"hint":"","explain":"<span class='basic_left'>Nhi\u1ec7t l\u01b0\u1ee3ng m\u00e0 n\u01b0\u1edbc nh\u1eadn v\u00e0o l\u00e0:<br\/> ${{Q}_{ci}}=mC\\Delta t=2\\times 80\\times 4200=672000J$ <br\/>Nhi\u1ec7t l\u01b0\u1ee3ng t\u1ecfa ra l\u00e0:<br\/>${{Q}_{tp}}=\\dfrac{{{Q}_{ci}}}{0,9}=\\dfrac{672000}{0,9}=74700J$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3003},{"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":"M\u1ed9t \u1ea5m \u0111i\u1ec7n c\u00f3 ghi 220V - 1000W \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng v\u1edbi hi\u1ec7u \u0111i\u1ec7n th\u1ebf 220V \u0111\u1ec3 \u0111un s\u00f4i 2l n\u01b0\u1edbc t\u1eeb nhi\u1ec7t \u0111\u1ed9 ban \u0111\u1ea7u $20{}^\\circ C$. Hi\u1ec7u su\u1ea5t c\u1ee7a \u1ea5m l\u00e0 90%, trong \u0111\u00f3 nhi\u1ec7t l\u01b0\u1ee3ng cung c\u1ea5p \u0111\u1ec3 \u0111un s\u00f4i n\u01b0\u1edbc \u0111\u01b0\u1edbc coi l\u00e0 c\u00f3 \u00edch. T\u00ednh th\u1eddi gian \u0111un s\u00f4i l\u01b0\u1ee3ng n\u01b0\u1edbc tr\u00ean.","select":["A. 746,7 s.","B. 724 s.","C. 570 s.","D. 660 s."],"hint":"","explain":"<span class='basic_left'>Nhi\u1ec7t l\u01b0\u1ee3ng m\u00e0 n\u01b0\u1edbc nh\u1eadn v\u00e0o l\u00e0:<br\/> ${{Q}_{ci}}=mC\\Delta t=2\\times 80\\times 4200=672000J$ <br\/>Nhi\u1ec7t l\u01b0\u1ee3ng t\u1ecfa ra l\u00e0:<br\/>${{Q}_{tp}}=\\dfrac{{{Q}_{ci}}}{0,9}=\\dfrac{672000}{0,9}=747000J$<br\/>Th\u1eddi gian \u0111un s\u00f4i n\u01b0\u1edbc:<br\/>$t=\\dfrac{{{Q}_{tp}}}{1000}=\\dfrac{746700}{1000}=746,7s$. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":3004},{"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":"\u0110\u01b0\u1eddng d\u00e2y d\u1eabn t\u1eeb m\u1ea1ng \u0111i\u1ec7n chung t\u00f3i m\u1ed9t gia \u0111\u00ecnh c\u00f3 chi\u1ec1u d\u00e0i t\u1ed5ng c\u1ed9ng l\u00e0 40m v\u00e0 c\u00f3 l\u00f5i \u0111\u1ed3ng v\u00f3i ti\u1ebft di\u1ec7n l\u00e0 $0,5m{{m}^{2}}$. Hi\u1ec7u \u0111i\u1ec7n th\u1ebf \u1edf cu\u1ed1i \u0111\u01b0\u1eddng d\u00e2y (t\u1ea1i nh\u00e0) l\u00e0 220V. Gia \u0111\u00ecnh n\u00e0y s\u1eed d\u1ee5ng c\u00e1c \u0111\u00e8n d\u00e2y t\u00f3c n\u00f3ng s\u00e1ng c\u00f3 t\u1ed5ng c\u00f4ng su\u1ea5t l\u00e0 165W trung b\u00ecnh 3 gi\u1edd m\u1ed7i ng\u00e0y. Bi\u1ebft \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a \u0111\u1ed3ng l\u00e0$1,7\\times {{10}^{-8}}\\Omega .m$. T\u00ednh \u0111i\u1ec7n tr\u1edf c\u1ee7a to\u00e0n b\u1ed9 \u0111\u01b0\u1eddng d\u00e2y d\u1eabn t\u1eeb m\u1ea1ng \u0111i\u1ec7n chung t\u1edbi gia \u0111\u00ecnh","select":["A. 1 \u03a9.","B. 2 \u03a9.","C. 1,36\u03a9.","D. 2,72 \u03a9."],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf c\u1ee7a to\u00e0n b\u1ed9 \u0111\u01b0\u1eddng d\u00e2y d\u1eabn t\u1eeb m\u1ea1ng \u0111i\u1ec7n chung t\u1edbi gia \u0111\u00ecnh:<br\/>$R=\\dfrac{\\rho l}{S}=\\dfrac{1,7\\times {{10}^{-8}}\\times 40}{0,5\\times {{10}^{-6}}}=1,36\\Omega $ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":3005},{"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":"\u0110\u01b0\u1eddng d\u00e2y d\u1eabn t\u1eeb m\u1ea1ng \u0111i\u1ec7n chung t\u00f3i m\u1ed9t gia \u0111\u00ecnh c\u00f3 chi\u1ec1u d\u00e0i t\u1ed5ng c\u1ed9ng l\u00e0 40m v\u00e0 c\u00f3 l\u00f5i \u0111\u1ed3ng v\u00f3i ti\u1ebft di\u1ec7n l\u00e0 $0,5m{{m}^{2}}$ . Hi\u1ec7u \u0111i\u1ec7n th\u1ebf \u1edf cu\u1ed1i \u0111\u01b0\u1eddng d\u00e2y (t\u1ea1i nh\u00e0) l\u00e0 220V. Gia \u0111\u00ecnh n\u00e0y s\u1eed d\u1ee5ng c\u00e1c \u0111\u00e8n d\u00e2y t\u00f3c n\u00f3ng s\u00e1ng c\u00f3 t\u1ed5ng c\u00f4ng su\u1ea5t l\u00e0 165W trung b\u00ecnh 3 gi\u1edd m\u1ed7i ng\u00e0y. Bi\u1ebft \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a \u0111\u1ed3ng l\u00e0 $1,7\\times {{10}^{-8}}\\Omega .m$. T\u00ednh c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y trong \u0111\u01b0\u1eddng d\u00e2y d\u1eabn khi s\u1eed d\u1ee5ng c\u00f4ng su\u1ea5t \u0111\u00e3 cho tr\u00ean \u0111\u00e2y.","select":["A. 0,25A.","B. 0,5A.","C. 0,75A.","D. 1A."],"hint":"","explain":"<span class='basic_left'>C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y trong \u0111\u01b0\u1eddng d\u00e2y d\u1eabn :<br\/>$I=\\dfrac{P}{U}=\\dfrac{165}{220}=0,75A$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":3006},{"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":"\u0110\u01b0\u1eddng d\u00e2y d\u1eabn t\u1eeb m\u1ea1ng \u0111i\u1ec7n chung t\u00f3i m\u1ed9t gia \u0111\u00ecnh c\u00f3 chi\u1ec1u d\u00e0i t\u1ed5ng c\u1ed9ng l\u00e0 40m v\u00e0 c\u00f3 l\u00f5i \u0111\u1ed3ng v\u00f3i ti\u1ebft di\u1ec7n l\u00e0 $0,5m{{m}^{2}}$. Hi\u1ec7u \u0111i\u1ec7n th\u1ebf \u1edf cu\u1ed1i \u0111\u01b0\u1eddng d\u00e2y (t\u1ea1i nh\u00e0) l\u00e0 220V. Gia \u0111\u00ecnh n\u00e0y s\u1eed d\u1ee5ng c\u00e1c \u0111\u00e8n d\u00e2y t\u00f3c n\u00f3ng s\u00e1ng c\u00f3 t\u1ed5ng c\u00f4ng su\u1ea5t l\u00e0 165W trung b\u00ecnh 3 gi\u1edd m\u1ed7i ng\u00e0y. Bi\u1ebft \u0111i\u1ec7n tr\u1edf su\u1ea5t c\u1ee7a \u0111\u1ed3ng l\u00e0 $1,7\\times {{10}^{-8}}\\Omega .m$. T\u00ednh nhi\u1ec7t l\u01b0\u1ee3ng t\u1ecfa ra tr\u00ean \u0111\u01b0\u1eddng d\u00e2y d\u1eabn n\u00e0y trong 30 ng\u00e0y theo \u0111\u01a1n v\u1ecb kW.h.","select":["A. 0,07 kW.h.","B. 0,05 kW.h.","C. 0,03 kW.h.","D. 0,02 kW.h."],"hint":"","explain":"<span class='basic_left'>\u0110i\u1ec7n tr\u1edf c\u1ee7a to\u00e0n b\u1ed9 \u0111\u01b0\u1eddng d\u00e2y d\u1eabn t\u1eeb m\u1ea1ng \u0111i\u1ec7n chung t\u1edbi gia \u0111\u00ecnh:<br\/>$R=\\dfrac{\\rho l}{S}=\\dfrac{1,7\\times {{10}^{-8}}\\times 40}{0,5\\times {{10}^{-6}}}=1,36\\Omega $ <br\/>C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n ch\u1ea1y trong \u0111\u01b0\u1eddng d\u00e2y d\u1eabn :<br\/> $I=\\dfrac{P}{U}=\\dfrac{165}{220}=0,75A$ <br\/>Nhi\u1ec7t l\u01b0\u1ee3ng t\u1ecfa ra tr\u00ean \u0111\u01b0\u1eddng d\u00e2y d\u1eabn n\u00e0y trong 30 ng\u00e0y :<br\/>$Q={{I}^{2}}Rt=0,{{75}^{2}}\\times 1,36\\times 3\\times 30=68,85Wh\\approx 0,07kWh$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":3007},{"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":"Hai \u0111i\u1ec7n tr\u1edf $R_1$ = 4\u2126 v\u00e0 $R_2$ = 6\u2126 \u0111\u01b0\u1ee3c m\u1eafc song song v\u00e0o hi\u1ec7u \u0111i\u1ec7n th\u1ebf U, trong c\u00f9ng th\u1eddi gian \u0111i\u1ec7n tr\u1edf n\u00e0o ti\u00eau th\u1ee5 \u0111i\u1ec7n n\u0103ng nhi\u1ec1u h\u01a1n v\u00e0 nhi\u1ec1u h\u01a1n bao nhi\u00eau l\u1ea7n?","select":["A. $R_1$ ti\u00eau th\u1ee5 \u0111i\u1ec7n n\u0103ng nhi\u1ec1u h\u01a1n $R_2$ g\u1ea5p 2 l\u1ea7n.","B. $R_1$ ti\u00eau th\u1ee5 \u0111i\u1ec7n n\u0103ng nhi\u1ec1u h\u01a1n $R_2$ g\u1ea5p 1,5 l\u1ea7n.","C. $R_2$ ti\u00eau th\u1ee5 \u0111i\u1ec7n n\u0103ng nhi\u1ec1u h\u01a1n $R_1$ g\u1ea5p 2 l\u1ea7n.","D. $R_2$ ti\u00eau th\u1ee5 \u0111i\u1ec7n n\u0103ng nhi\u1ec1u h\u01a1n $R_1$ g\u1ea5p 1,5 l\u1ea7n."],"hint":"","explain":"<span class='basic_left'>${{P}_{1}}=\\dfrac{{{U}^{2}}}{{{R}_{1}}}$ <br\/>${{P}_{2}}=\\dfrac{{{U}^{2}}}{{{R}_{2}}}$<br\/>$\\dfrac{{{P}_{1}}}{{{P}_{2}}}=\\dfrac{{{R}_{2}}}{{{R}_{1}}}=\\dfrac{6}{4}=1,5$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3008},{"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\u00e0n l\u00e0 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u1edf hi\u1ec7u \u0111i\u1ec7n th\u1ebf \u0111\u1ecbnh m\u1ee9c 220V trong 10 ph\u00fat th\u00ec ti\u00eau th\u1ee5 m\u1ed9t l\u01b0\u1ee3ng \u0111i\u1ec7n n\u0103ng l\u00e0 660kJ. C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n qua b\u00e0n l\u00e0 l\u00e0:","select":["A. 0,5 A.","B. 0,3A.","C. 3A.","D. 5A."],"hint":"","explain":"<span class='basic_left'>$A=UIt\\Rightarrow I=\\dfrac{A}{Ut}=\\dfrac{660000}{220\\times 10\\times 60}=5A$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":3009},{"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 \u0111\u00e8n lo\u1ea1i 220V \u2013 75W v\u00e0 m\u1ed9t \u0111\u00e8n lo\u1ea1i 220V \u2013 25W \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u00fang hi\u1ec7u \u0111i\u1ec7n th\u1ebf \u0111\u1ecbnh m\u1ee9c. Trong c\u00f9ng th\u1eddi gian, so s\u00e1nh \u0111i\u1ec7n n\u0103ng ti\u00eau th\u1ee5 c\u1ee7a hai \u0111\u00e8n:","select":["A. ${{A}_{1}}={{A}_{2}}$ .","B. ${{A}_{1}}=3{{A}_{2}}$.","C. $3{{A}_{1}}={{A}_{2}}$.","D. ${{A}_{1}}<{{A}_{2}}$."],"hint":"","explain":"<span class='basic_left'>${{P}_{1}}>{{P}_{2}}\\Rightarrow {{A}_{1}}>{{A}_{2}}$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":3010}],"lesson":{"save":0,"level":2}}