Kh\u00f4ng ch\u1ec9 c\u00e1c m\u00f4n khoa h\u1ecdc x\u00e3 h\u1ed9i v\u00e0 nh\u00e2n v\u0103n m\u1edbi y\u00eau c\u1ea7u v\u1eadn d\u1ee5ng ki\u1ebfn th\u1ee9c v\u00e0o th\u1ef1c ti\u1ec5n, g\u1eafn v\u1edbi v\u1ea5n \u0111\u1ec1 th\u1eddi s\u1ef1, \u0111\u1ec1 thi c\u00e1c m\u00f4n khoa h\u1ecdc t\u1ef1 nhi\u00ean c\u0169ng kh\u00f4ng \u0111i tr\u1eadt xu h\u01b0\u1edbng ra \u0111\u1ec1 n\u00e0y. Khi \u00f4n luy\u1ec7n V\u1eadt l\u00fd, h\u1ecdc sinh c\u1ea7n \u0111\u1eb7c bi\u1ec7t ch\u00fa \u00fd t\u1edbi nh\u1eefng d\u1ea1ng b\u00e0i v\u1ec1 hi\u1ec7n t\u01b0\u1ee3ng th\u1ef1c ti\u1ec5n, cu\u1ed9c s\u1ed1ng. \u0110i\u1ec3m y\u1ebfu c\u1ee7a h\u1ecdc sinh trong qu\u00e1 tr\u00ecnh \u00f4n luy\u1ec7n th\u01b0\u1eddng l\u00e0 qu\u00e1 ch\u00fa tr\u1ecdng c\u00f4ng th\u1ee9c m\u00e0 coi nh\u1eb9 k\u1ef9 n\u0103ng \u0111\u1ecdc hi\u1ec7n t\u01b0\u1ee3ng, trong khi ch\u1ec9 c\u1ea7n \u0111\u1ec3 \u00fd m\u1ed9t ch\u00fat l\u00e0 h\u1ecdc sinh c\u00f3 th\u1ec3 gi\u1ea3i quy\u1ebft \u0111\u01b0\u1ee3c nh\u1eefng c\u00e2u h\u1ecfi trong d\u1ea1ng n\u00e0y.<\/p>\n

R\u1ea5t d\u1ec5 b\u1eaft g\u1eb7p nh\u1eefng d\u1ea1ng b\u00e0i \u0111\u1ecdc hi\u1ec7n t\u01b0\u1ee3ng \u0111\u01a1n thu\u1ea7n trong \u0111\u1ec1 thi, \u0111\u00e2y l\u00e0 d\u1ea1ng b\u00e0i kh\u00f4ng kh\u00f3 nh\u01b0ng y\u00eau c\u1ea7u h\u1ecdc sinh ph\u1ea3i th\u00f4ng hi\u1ec3u hi\u1ec7n t\u01b0\u1ee3ng v\u00e0 c\u00f3 kh\u1ea3 n\u0103ng li\u00ean h\u1ec7 th\u1ef1c ti\u1ec5n, \u0111\u1eddi s\u1ed1ng. N\u1ebfu kh\u00f4ng ch\u00fa \u00fd trong qu\u00e1 tr\u00ecnh \u00f4n luy\u1ec7n, h\u1ecdc sinh s\u1ebd m\u1ea5t \u0111i\u1ec3m \u1edf nh\u1eefng c\u00e2u h\u1ecfi \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 \u1edf m\u1ee9c \u0111\u1ed9 kh\u00f4ng qu\u00e1 kh\u00f3.<\/p>\n

D\u01b0\u1edbi \u0111\u00e2y m\u1ed9t s\u1ed1 c\u00e2u h\u1ecfi th\u1ef1c ti\u1ec5n c\u00f3 th\u1ec3 xu\u1ea5t hi\u1ec7n trong \u0111\u1ec1 thi V\u1eadt l\u00fd nh\u1eb1m gi\u00fap h\u1ecdc sinh l\u00e0m quen, t\u1eadp \u0111\u00e1nh gi\u00e1, ph\u00e2n t\u00edch hi\u1ec7n t\u01b0\u1ee3ng \u0111\u1ec3 l\u1ef1a ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0111\u00fang nh\u1ea5t (ph\u01b0\u01a1ng \u00e1n g\u1ea1ch ch\u00e2n l\u00e0 ph\u01b0\u01a1ng \u00e1n \u0111\u00fang). <\/em><\/p>\n

V\u00ed d\u1ee5 1:<\/strong> M\u1ed9t h\u00e0nh kh\u00e1ch \u0111i v\u1ec1 ph\u00eda c\u1eeda v\u00e0o nh\u00e0 ga C\u1ea3ng H\u00e0ng kh\u00f4ng qu\u1ed1c t\u1ebf N\u1ed9i B\u00e0i th\u00ec th\u1ea5y hai t\u1ea5m c\u1eeda k\u00ednh \u0111ang kh\u00e9p l\u1ea1i. Nh\u01b0ng khi anh ta l\u1ea1i g\u1ea7n th\u00ec l\u1ea1 thay (!), hai t\u1ea5m c\u1eeda k\u00ednh t\u1ef1 \u0111\u1ed9ng t\u00e1ch xa nhau, khi anh ta \u0111i v\u00e0o trong nh\u00e0 ga thi hai t\u1ea5m c\u1eeda k\u00ednh l\u1ea1i kh\u00e9p l\u1ea1i nh\u01b0 c\u0169. Thi\u1ebft b\u1ecb \u0111\u00f3ng \u2013 m\u1edf c\u1eeda nh\u00e0 ga \u1edf \u0111\u00e2y \u0111ang ho\u1ea1t \u0111\u1ed9ng d\u1ef1a tr\u00ean hi\u1ec7n t\u01b0\u1ee3ng<\/p>\n

A. <\/strong>Hi\u1ec7n t\u01b0\u1ee3ng quang \u0111i\u1ec7n ngo\u00e0i.<\/u><\/strong><\/p>\n

B. Hi\u1ec7n t\u01b0\u1ee3ng quang \u0111i\u1ec7n trong.<\/p>\n

C. Hi\u1ec7n t\u01b0\u1ee3ng quang ph\u00e1t quang.<\/p>\n

D. Kh\u00f4ng ph\u1ea3i nh\u1eefng hi\u1ec7n t\u01b0\u1ee3ng tr\u00ean.<\/p>\n

H\u01b0\u1edbng d\u1eabn v\u00e0 ph\u00e2n t\u00edch: V\u1edbi c\u00e2u h\u1ecfi n\u00e0y, nhi\u1ec1u h\u1ecdc sinh s\u1ebd ch\u1ecdn nh\u1ea7m hi\u1ec7n t\u01b0\u1ee3ng quang \u0111i\u1ec7n trong, b\u1edfi h\u1ea7u h\u1ebft c\u00e1c \u1ee9ng d\u1ee5ng th\u1ef1c t\u1ebf \u0111\u1ec1u b\u1edfi hi\u1ec7n t\u01b0\u1ee3ng quang \u0111i\u1ec7n, nh\u01b0ng hi\u1ec7n t\u01b0\u1ee3ng trong c\u00e2u h\u1ecfi th\u00e0y thu\u1ed9c s\u1ed1 \u00edt c\u00e1c c\u00e1c \u1ee9ng d\u1ee5ng c\u1ee7a hi\u1ec7n t\u01b0\u1ee3ng quang \u0111i\u1ec7n ngo\u00e0i.<\/em><\/p>\n

V\u00ed d\u1ee5 2:<\/strong> Hi\u1ec7n nay \u0111\u00e8n LED \u0111ang c\u00f3 nh\u1eefng b\u01b0\u1edbc nh\u1ea3y v\u1ecdt trong \u1ee9ng d\u1ee5ng th\u1ecb tr\u01b0\u1eddng d\u00e2n d\u1ee5ng v\u00e0 c\u00f4ng nghi\u1ec7p m\u1ed9t c\u00e1ch r\u1ed9ng r\u00e3i nh\u01b0 b\u1ed9 ph\u1eadn hi\u1ec3n th\u1ecb trong c\u00e1c thi\u1ebft b\u1ecb \u0111i\u1ec7n t\u1eed, \u0111\u00e8n qu\u1ea3ng c\u00e1o, \u0111\u00e8n giao th\u00f4ng, trang tr\u00ed n\u1ed9i th\u1ea5t, ngo\u1ea1i th\u1ea5t\u2026 Nguy\u00ean l\u00fd ho\u1ea1t \u0111\u1ed9ng c\u1ee7a \u0111\u00e8n LED d\u1ef1a v\u00e0o hi\u1ec7n t\u01b0\u1ee3ng:<\/p>\n

A. Quang ph\u00e1t quang.<\/p>\n

B. H\u00f3a ph\u00e1t quang.<\/p>\n

C. <\/strong>\u0110i\u1ec7n ph\u00e1t quang.<\/u><\/strong><\/p>\n

D. Cat\u00f4t ph\u00e1t quang.<\/p>\n

H\u01b0\u1edbng d\u1eabn v\u00e0 ph\u00e2n t\u00edch: V\u1edbi c\u00e2u h\u1ecfi n\u00e0y, d\u00f9 h\u1ecdc sinh c\u00f3 kh\u1ea3 n\u0103ng suy lu\u1eadn \u0111\u00e3 lo\u1ea1i b\u1ecf \u0111\u01b0\u1ee3c \u0111\u00e1p \u00e1n A v\u00e0 B th\u00ec c\u0169ng kh\u00f3 kh\u0103n trong vi\u1ec7c t\u00ecm \u0111\u00e1p \u00e1n \u0111\u00fang n\u1ebfu kh\u00f4ng h\u1ecdc k\u0129 SGK ph\u1ea7n ch\u1eef in nh\u1ecf trong b\u00e0i quang ph\u00e1t quang.<\/em><\/p>\n

V\u00ed d\u1ee5 3:<\/strong> L\u00f2 ph\u1ea3n \u1ee9ng h\u1ea1t nh\u00e2n l\u00e0 m\u1ed9t thi\u1ebft b\u1ecb \u0111\u1ec3 kh\u1edfi \u0111\u1ed9ng, ki\u1ec3m so\u00e1t, v\u00e0 duy tr\u00ec m\u1ed9t chu\u1ed7i ph\u1ea3n \u1ee9ng chu\u1ed7i h\u1ea1t nh\u00e2n. L\u00f2 ph\u1ea3n \u1ee9ng h\u1ea1t nh\u00e2n th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 t\u1ea1o ra \u0111i\u1ec7n v\u00e0 cung c\u1ea5p n\u0103ng l\u01b0\u1ee3ng cho m\u1ed9t s\u1ed1 t\u00e0u ng\u1ea7m, t\u00e0u s\u00e2n bay\u2026m\u00e0 hi\u1ec7n nay qu\u00e2n \u0111\u1ed9i Hoa K\u00ec ph\u00e1t tri\u1ec3n r\u1ea5t m\u1ea1nh. Nhi\u00ean li\u1ec7u trong c\u00e1c l\u00f2 n\u00e0y th\u01b0\u1eddng l\u00e0 ho\u1eb7c P239. S\u1ef1 ph\u00e2n h\u1ea1ch c\u1ee7a m\u1ed9t h\u1ea1t nh\u00e2n U235 c\u00f3 k\u00e8m theo gi\u1ea3i ph\u00f3ng 2,5 n\u01a1tron (t\u00ednh trung b\u00ecnh), \u0111\u1ed1i v\u1edbi P239 con s\u1ed1 \u0111\u00f3 l\u00e0 3. C\u00e1c n\u01a1tron n\u00e0y c\u00f3 th\u1ec3 k\u00edch th\u00edch c\u00e1c h\u1ea1t nh\u00e2n kh\u00e1c ph\u00e2n h\u1ea1ch \u0111\u1ec3 t\u1ea1o n\u00ean m\u1ed9t ph\u1ea3n \u1ee9ng d\u00e2y truy\u1ec1n n\u1ebfu kh\u00f4ng \u0111\u01b0\u1ee3c \u0111i\u1ec1u khi\u1ec3n. C\u00e1c l\u00f2 ph\u1ea3n \u1ee9ng h\u1ea1t nh\u00e2n \u0111\u01b0\u1ee3c \u0111i\u1ec1u khi\u1ec3n \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o n\u0103ng l\u01b0\u1ee3ng t\u1ecfa ra t\u1eeb l\u00f2 ph\u1ea3n \u1ee9ng l\u00e0 kh\u00f4ng \u0111\u1ed5i theo th\u1eddi gian, trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y ng\u01b0\u1eddi ta th\u01b0\u1eddng d\u00f9ng nh\u1eefng thanh \u0111i\u1ec1u khi\u1ec3n ng\u1eadp s\u00e2u v\u00e0o trong l\u00f2 \u0111\u1ec3 h\u1ea5p th\u1ee5 s\u1ed1 n\u01a1tron th\u1eeba v\u00e0 \u0111\u1ea3m b\u1ea3o s\u1ed1 n\u01a1tron gi\u1ea3i ph\u00f3ng sau m\u1ed7i ph\u00e2n h\u1ea1ch l\u00e0 1 (t\u00ednh trung b\u00ecnh). Thanh \u0111i\u1ec1u khi\u1ec3n c\u00f3 ch\u1ee9a:<\/p>\n

A. B\u1ea1ch kim<\/p>\n

B. V\u00e0ng ho\u1eb7c nh\u1eefng kim lo\u1ea1i c\u00f3 nguy\u00ean t\u1eed l\u01b0\u1ee3ng l\u1edbn.<\/p>\n

C. <\/strong>Bo ho\u1eb7c Ca\u0111imi<\/u><\/strong><\/p>\n

D. N\u01b0\u1edbc<\/p>\n

H\u01b0\u1edbng d\u1eabn v\u00e0 ph\u00e2n t\u00edch: N\u1ebfu h\u1ecdc sinh kh\u00f4ng \u0111\u1ecdc k\u0129 SGK v\u1ec1 l\u00f2 ph\u1ea3n \u1ee9ng h\u1ea1t nh\u1eadn h\u1ecdc sinh s\u1ebd kh\u00f4ng l\u00e0m \u0111\u01b0\u1ee3c c\u00e2u n\u00e0y.<\/em><\/p>\n

V\u00ed d\u1ee5 4:<\/strong> M\u1ed9t ng\u01b0\u1eddi \u0111i xe m\u00e1y tr\u00ean \u0111o\u1ea1n \u0111\u01b0\u1eddng c\u1ee9 6 m l\u1ea1i c\u00f3 \u1ed5 g\u00e0, t\u1ea7n s\u1ed1 dao \u0111\u1ed9ng khung xe l\u00e0 2 Hz. \u0110\u1ec3 tr\u00e1nh rung l\u1eafc m\u1ea1nh nh\u1ea5t ng\u01b0\u1eddi \u0111\u00f3 ph\u1ea3i tr\u00e1nh t\u1ed1c \u0111\u1ed9 n\u00e0o sau \u0111\u00e2y?<\/p>\n

A. <\/strong>43,2 km\/h.<\/u><\/strong><\/p>\n

B. 21,6 km\/h.<\/p>\n

C. 36,0 km\/h.<\/p>\n

D. 18,0 km\/h.<\/p>\n

H\u01b0\u1edbng d\u1eabn v\u00e0 ph\u00e2n t\u00edch: Trong b\u00e0i to\u00e1n th\u1ef1c t\u1ebf n\u00e0y, h\u1ecdc sinh c\u1ea7n nh\u1edb v\u1ec1 \u0111i\u1ec1u ki\u1ec7n x\u1ea3y ra hi\u1ec7n t\u01b0\u1ee3ng c\u1ed9ng h\u01b0\u1edfng (khi \u0111\u00f3 xe rung l\u1eafc m\u1ea1nh nh\u1ea5t), \u0111\u00f3 l\u00e0 t\u1ea7n s\u1ed1 (chu k\u00ec) ngo\u1ea1i l\u1ef1c c\u01b0\u1ee1ng b\u1ee9c x\u1ea5p x\u1ec9 b\u1eb1ng t\u1ea7n s\u1ed1 (chu k\u00ec) dao \u0111\u1ed9ng ri\u00eang c\u1ee7a h\u1ec7 dao \u0111\u1ed9ng. \u1ede \u0111\u00e2y, chu k\u00ec dao \u0111\u1ed9ng ri\u00eang b\u00e0i cho To = 1\/f = 0,5 s. Ta coi ngo\u1ea1i l\u1ef1c c\u01b0\u1ee1ng b\u1ee9c l\u00ean xe khi g\u1eb7p \u1ed5 g\u00e0 c\u00f3 chu k\u00ec l\u00e0 T = 6\/v, v l\u00e0 t\u1ed1c \u0111\u1ed9 xe. Ta c\u00f3: T = To \u2192 v = 12 m\/s = 43,2 km\/h. <\/em><\/p>\n

V\u00ed d\u1ee5 5:<\/strong> M\u1ea1ng \u0111i\u1ec7n d\u00e2n d\u1ee5ng \u1edf Vi\u1ec7t Nam c\u00f3 \u0111i\u1ec7n \u00e1p hi\u1ec7u d\u1ee5ng l\u00e0 220 V, \u1edf Nh\u1eadt l\u00e0 110\u2026 \u0110i\u1ec7n \u00e1p hi\u1ec7u d\u1ee5ng qu\u00e1 cao, c\u00f3 th\u1ec3 g\u00e2y nhi\u1ec1u nguy hi\u1ec3m cho ng\u01b0\u1eddi s\u1eed d\u1ee5ng. N\u1ebfu \u0111i\u1ec7n \u00e1p hi\u1ec7u d\u1ee5ng th\u1ea5p, ch\u1eb3ng h\u1ea1n 30V-50 V s\u1ebd \u00edt g\u00e2y nguy hi\u1ec3m cho ng\u01b0\u1eddi s\u1eed d\u1ee5ng. Nguy\u00ean nh\u00e2n kh\u00f4ng s\u1eed d\u1ee5ng m\u1ea1ng \u0111i\u1ec7n c\u00f3 \u0111i\u1ec7n \u00e1p hi\u1ec7u d\u1ee5ng th\u1ea5p:<\/p>\n

A. Kh\u00f4ng th\u1ec3 s\u1ea3n xu\u1ea5t linh ki\u1ec7n \u0111i\u1ec7n s\u1eed d\u1ee5ng.<\/p>\n

B. <\/strong>C\u00f4ng su\u1ea5t hao ph\u00ed s\u1ebd qu\u00e1 l\u1edbn.<\/u><\/strong><\/p>\n

C. C\u00f4ng su\u1ea5t n\u01a1i truy\u1ec1n t\u1ea3i s\u1ebd qu\u00e1 nh\u1ecf.<\/p>\n

D. C\u00f4ng su\u1ea5t n\u01a1i ti\u00eau th\u1ee5 s\u1ebd qu\u00e1 l\u1edbn.<\/p>\n

H\u01b0\u1edbng d\u1eabn v\u00e0 ph\u00e2n t\u00edch: \u1ede \u0111\u00e2y, khi s\u1eed d\u1ee5ng m\u1ea1ng \u0111i\u1ec7n c\u00f3 \u0111i\u1ec7n \u00e1p hi\u1ec7u d\u1ee5ng nh\u1ecf d\u1eabn t\u1edbi c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng hi\u1ec7u d\u1ee5ng trong truy\u1ec1n t\u1ea3i s\u1ebd l\u1edbn, do \u0111\u00f3 c\u00f4ng su\u1ea5t hao ph\u00ed s\u1ebd r\u1ea5t l\u1edbn. \u0110\u1ec3 \u0111\u1ea3m b\u1ea3o c\u00f4ng su\u1ea5t hao ph\u00ed nh\u1ecf \u0111i, c\u00e1c d\u00e2y d\u1eabn \u0111i\u1ec7n s\u1ebd ph\u1ea3i l\u00e0m r\u1ea5t r\u1ea5t to \u0111\u1ec3 \u0111i\u1ec7n tr\u1edf gi\u1ea3m, thi\u1ec7t h\u1ea1i nhi\u1ec1u v\u1ec1 kinh t\u1ebf! V\u1ea5n \u0111\u1ec1 \u1edf \u0111\u00e2y l\u00e0 kinh t\u1ebf, c\u00f2n ho\u00e0n to\u00e0n c\u00f3 th\u1ec3 t\u1ea1o ra m\u1ea1ng \u0111i\u1ec7n c\u00f3 \u0111i\u1ec7n \u00e1p hi\u1ec7u d\u1ee5ng th\u1ea5p nh\u01b0 v\u1eady! <\/em><\/p>\n

Ngo\u00e0i nh\u1eefng d\u1ea1ng b\u00e0i c\u00f3 hi\u1ec7n t\u01b0\u1ee3ng \u0111\u01a1n gi\u1ea3n nh\u01b0 v\u1eady th\u00ec \u0111\u1ec1 thi c\u00f3 th\u1ec3 c\u00f3 nh\u1eefng b\u00e0i to\u00e1n k\u1ebft h\u1ee3p hi\u1ec7n t\u01b0\u1ee3ng r\u1ea5t kh\u00f3, y\u00eau c\u1ea7u th\u00ed sinh c\u00f3 t\u01b0 duy V\u1eadt l\u00ed, kh\u1ea3 n\u0103ng \u0111\u1ecdc hi\u1ec7n t\u01b0\u1ee3ng, k\u1ebft h\u1ee3p linh ho\u1ea1t gi\u1eefa c\u00e1c \u0111\u1ecbnh lu\u1eadt, c\u00f4ng th\u1ee9c li\u00ean quan, d\u0129 nhi\u00ean k\u0129 n\u0103ng to\u00e1n h\u1ecdc c\u0169ng ph\u1ea3i t\u1ed1t. M\u1ed9t v\u00e0i v\u00ed d\u1ee5 tham kh\u1ea3o nh\u01b0:<\/p>\n\n\n\n

<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n \u00a0Th\u1ea7y \u0110\u1ed7 Ng\u1ecdc H\u00e0<\/strong><\/p>\n<\/div>\n<\/div>\n Gi\u00e1o vi\u00ean luy\u1ec7n thi m\u00f4n V\u1eadt ly , H\u1ec7 th\u1ed1ng gi\u00e1o d\u1ee5c Hocmai.vn<\/em><\/p>\n","protected":false},"excerpt":{"rendered":" C\u00e2u h\u1ecfi th\u1ef1c ti\u1ec5n kh\u00f4ng kh\u00f3 nh\u01b0ng y\u00eau c\u1ea7u h\u1ecdc sinh ph\u1ea3i th\u00f4ng hi\u1ec3u hi\u1ec7n t\u01b0\u1ee3ng v\u00e0 kh\u1ea3 n\u0103ng li\u00ean h\u1ec7 \u0111\u1eddi s\u1ed1ng. N\u1ebfu kh\u00f4ng ch\u00fa \u00fd \u00f4n luy\u1ec7n, h\u1ecdc sinh s\u1ebd d\u1ec5 m\u1ea5t \u0111i\u1ec3m. Kh\u00f4ng ch\u1ec9 c\u00e1c m\u00f4n khoa h\u1ecdc x\u00e3 h\u1ed9i v\u00e0 nh\u00e2n v\u0103n m\u1edbi y\u00eau c\u1ea7u v\u1eadn d\u1ee5ng ki\u1ebfn th\u1ee9c v\u00e0o th\u1ef1c […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false,"tdm_status":"","tdm_grid_status":""},"categories":[158],"tags":[],"yoast_head":"\n