{"id":1179,"date":"2021-10-09T00:50:00","date_gmt":"2021-10-09T00:50:00","guid":{"rendered":"https:\/\/www.vietlearn.org\/post\/?p=1179"},"modified":"2021-10-14T22:12:06","modified_gmt":"2021-10-14T15:12:06","slug":"hien-tuong-khuc-xa-anh-sang-la-gi-kien-thuc-vat-ly-9","status":"publish","type":"post","link":"https:\/\/www.vietlearn.org\/kien-thuc\/hien-tuong-khuc-xa-anh-sang-la-gi-kien-thuc-vat-ly-9\/","title":{"rendered":"Hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng l\u00e0 g\u00ec? Ki\u1ebfn th\u1ee9c v\u1eadt l\u00fd 9"},"content":{"rendered":"\n

Ghi ch\u00fa: T\u00e0i li\u1ec7u tr\u00edch d\u1eabn<\/p>\n\n\n\n

Trong cu\u1ed9c s\u1ed1ng, ch\u1eafc ch\u1eafn s\u1ebd c\u00f3 nhi\u1ec1u l\u00fac c\u00e1c em g\u1eb7p hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1. V\u00ed d\u1ee5, khi c\u00e1c em \u0111ang khu\u1ea5y m\u1ed9t c\u1ed1c n\u01b0\u1edbc \u0111\u01b0\u1eddng, s\u1eed d\u1ee5ng th\u00eca ho\u1eb7c mu\u1ed7ng khu\u1ea5y, c\u00e1c em s\u1ebd th\u1ea5y \u0111\u01b0\u1ee3c hi\u1ec7n t\u01b0\u1ee3ng n\u00e0y. Qua m\u1eb7t ph\u00e2n c\u00e1ch gi\u1eefa kh\u00f4ng kh\u00ed v\u00e0 n\u01b0\u1edbc, ph\u1ea7n c\u00e1n th\u00eca ho\u1eb7c mu\u1ed7ng b\u1ecb l\u1ec7ch \u0111i tr\u00f4ng th\u1ea5y. C\u00e1c em c\u00f3 bao gi\u1edd th\u1eafc m\u1eafc l\u00fd do t\u1ea1i sao kh\u00f4ng? N\u1ebfu mu\u1ed1n t\u00ecm hi\u1ec3u c\u00e2u tr\u1ea3 l\u1eddi t\u1eeb hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng, c\u00f9ng \u0111\u1ecdc ti\u1ebfp b\u00e0i vi\u1ebft n\u00e0y nh\u00e9. Ch\u00fang t\u00f4i mang \u0111\u1ebfn cho c\u00e1c em nh\u1eefng chia s\u1ebb th\u00fa v\u1ecb nh\u1ea5t, \u0111\u1ea3m b\u1ea3o c\u00e1c em s\u1ebd kh\u00f4ng th\u1ea5y ki\u1ebfn th\u1ee9c n\u00e0y nh\u00e0m ch\u00e1n. C\u00f9ng b\u1eaft \u0111\u1ea7u th\u00f4i.<\/p>\n\n\n\n

Th\u1ef1c t\u1ebf kh\u00fac x\u1ea1 nh\u01b0 th\u1ebf n\u00e0o?<\/p>\n\n\n\n

Hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng l\u00e0 g\u00ec?<\/p>\n\n\n\n

Hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng l\u00e0 hi\u1ec7n t\u01b0\u1ee3ng \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a kh\u00e1 \u0111\u01a1n gi\u1ea3n. \u0110\u00e2y l\u00e0 hi\u1ec7n t\u01b0\u1ee3ng tia s\u00e1ng truy\u1ec1n t\u1eeb m\u00f4i tr\u01b0\u1eddng trong su\u1ed1t n\u00e0y \u0111\u1ebfn m\u00f4i tr\u01b0\u1eddng trong su\u1ed1t kh\u00e1c. Trong qu\u00e1 tr\u00ecnh truy\u1ec1n, ch\u00fang b\u1ecb g\u00e3y kh\u00fac ng\u00e0y m\u1eb7t ph\u00e2n c\u00e1ch \u1edf gi\u1eefa hai m\u00f4i tr\u01b0\u1eddng, t\u1ea1o ra hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1.<\/p>\n\n\n\n

G\u00f3c t\u1edbi, g\u00f3c ph\u1ea3n x\u1ea1 trong hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng l\u00e0 g\u00ec?<\/p>\n\n\n\n

Trong s\u1ef1 kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng, g\u00f3c t\u1edbi l\u00e0 g\u00f3c \u0111\u01b0\u1ee3c h\u1ee3p b\u1edfi tia t\u1edbi v\u00e0 ph\u00e1p tuy\u1ebfn c\u1ee7a m\u1eb7t ph\u1eb3ng. Kh\u00e1c v\u1edbi g\u00f3c t\u1edbi l\u00e0 g\u00f3c ph\u1ea3n x\u1ea1. G\u00f3c ph\u1ea3n x\u1ea1 l\u00e0 g\u00f3c \u0111\u01b0\u1ee3c h\u1ee3p b\u1edfi tia ph\u1ea3n x\u1ea1 c\u00f9ng v\u1edbi ph\u00e1p tuy\u1ebfn c\u1ee7a m\u1eb7t ph\u1eb3ng.<\/p>\n\n\n\n

S\u1ef1 kh\u00fac x\u1ea1 c\u1ee7a tia s\u00e1ng<\/p>\n\n\n\n

Nh\u00ecn v\u00e0o hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng, ta c\u00f3 th\u1ec3 th\u1ea5y c\u00f3 hai tr\u01b0\u1eddng h\u1ee3p xu\u1ea5t hi\u1ec7n. N\u1ebfu x\u00e9t \u1edf tr\u00ean hai m\u00f4i tr\u01b0\u1eddng l\u00e0 kh\u00f4ng kh\u00ed v\u00e0 n\u01b0\u1edbc, tia s\u00e1ng s\u1ebd c\u00f3 nh\u1eefng \u0111i\u1ec3m xu\u1ea5t ph\u00e1t kh\u00e1c nhau. Do \u0111\u00f3, ta x\u00e9t khi tia s\u00e1ng truy\u1ec1n t\u1eeb kh\u00f4ng kh\u00ed sang n\u01b0\u1edbc. V\u00e0 m\u1ed9t tr\u01b0\u1eddng h\u1ee3p kh\u00e1c l\u00e0 khi tia s\u00e1ng truy\u1ec1n t\u1eeb n\u01b0\u1edbc sang kh\u00f4ng kh\u00ed.<\/p>\n\n\n\n

N\u1ebfu tia s\u00e1ng truy\u1ec1n t\u1eeb kh\u00f4ng kh\u00ed sang n\u01b0\u1edbc, ta s\u1ebd th\u1ea5y hi\u1ec7n t\u01b0\u1ee3ng sau. Tia kh\u00fac x\u1ea1 s\u1ebd \u0111\u01b0\u1ee3c n\u1eb1m \u1edf trong m\u1eb7t ph\u1eb3ng t\u1edbi. Ngo\u00e0i ra, g\u00f3c kh\u00fac x\u1ea1 s\u1ebd nh\u1ecf h\u01a1n g\u00f3c t\u1edbi.<\/p>\n\n\n\n

N\u1ebfu nh\u01b0 tia s\u00e1ng truy\u1ec1n t\u1eeb m\u00f4i tr\u01b0\u1eddng n\u01b0\u1edbc sang m\u00f4i tr\u01b0\u1eddng kh\u00f4ng kh\u00ed. Tia kh\u00fac x\u1ea1 s\u1ebd n\u1eb1m trong m\u1eb7t ph\u1eb3ng t\u1edbi (t\u01b0\u01a1ng t\u1ef1 nh\u01b0 tr\u01b0\u1eddng h\u1ee3p tr\u00ean). G\u00f3c kh\u00fac x\u1ea1 s\u1ebd l\u1edbn h\u01a1n g\u00f3c t\u1edbi (ng\u01b0\u1ee3c v\u1edbi tr\u01b0\u1eddng h\u1ee3p tr\u00ean).<\/p>\n\n\n\n

Gi\u1ea3i \u0111\u00e1p chi ti\u1ebft hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng<\/p>\n\n\n\n

Nh\u1eefng ki\u1ebfn th\u1ee9c kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng m\u00e0 ch\u00fang t\u00f4i n\u00eau tr\u00ean ph\u00f9 h\u1ee3p v\u1edbi s\u1ef1 hi\u1ec3u bi\u1ebft c\u1ee7a h\u1ecdc sinh<\/a> kh\u1ed1i Trung h\u1ecdc c\u01a1 s\u1edf. Trong hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng, c\u00f2n r\u1ea5t nhi\u1ec1u th\u00f4ng tin li\u00ean quan kh\u00e1c. Th\u1ebf n\u00ean n\u1ebfu b\u1ea1n mu\u1ed1n \u0111\u00e0o s\u00e2u h\u01a1n v\u1ec1 hi\u1ec7n t\u01b0\u1ee3ng n\u00e0y, h\u00e3y \u0111\u1ecdc ngay ph\u1ea7n th\u00f4ng tin d\u01b0\u1edbi \u0111\u00e2y nh\u00e9.<\/p>\n\n\n\n

Th\u00ed nghi\u1ec7m v\u1ec1 hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng<\/p>\n\n\n\n

\u0110\u1ecbnh ngh\u0129a kh\u00fac x\u1ea1<\/p>\n\n\n\n

Kh\u00fac x\u1ea1 hay c\u00f2n \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 chi\u1ebft x\u1ea1. Ch\u00fang l\u00e0 c\u1ee5m t\u1eeb \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 ch\u1ec9 ra hi\u1ec7n t\u01b0\u1ee3ng \u00e1nh s\u00e1ng \u0111\u1ed5i h\u01b0\u1edbng khi \u0111i qua nh\u1eefng m\u1eb7t ph\u00e2n c\u00e1ch gi\u1eefa hai m\u00f4i tr\u01b0\u1eddng. M\u00f4i tr\u01b0\u1eddng \u1edf \u0111\u00e2y ph\u1ea3i \u0111\u1ea3m b\u1ea3o l\u00e0 trong su\u1ed1t, v\u00e0 c\u00f3 chi\u1ebft su\u1ea5t kh\u00e1c nhau.<\/p>\n\n\n\n

C\u00f3 th\u1ec3 hi\u1ec3u r\u1eb1ng, \u0111\u00e2y l\u00e0 hi\u1ec7n t\u01b0\u1ee3ng \u0111\u1ed5i h\u01b0\u1edbng \u0111\u01b0\u1eddng \u0111i c\u1ee7a b\u1ee9c x\u1ea1 \u0111i\u1ec7n t\u1eeb. Nhi\u1ec1u ng\u01b0\u1eddi s\u1ebd g\u1ecdi \u0111\u00e2y l\u00e0 c\u00e1c s\u00f3ng n\u00f3i chung, lan truy\u1ec1n b\u00ean trong c\u00e1c m\u00f4i tr\u01b0\u1eddng kh\u00f4ng ho\u00e0n to\u00e0n \u0111\u1ed3ng nh\u1ea5t. Th\u1ebf n\u00ean, hi\u1ec7n t\u01b0\u1ee3ng n\u00e0y c\u00f3 th\u1ec3 gi\u1ea3i th\u00edch cho hi\u1ec7n t\u01b0\u1ee3ng b\u1ea3o to\u00e0n \u0111\u1ed9ng l\u01b0\u1ee3ng ho\u1eb7c hi\u1ec7n t\u01b0\u1ee3ng b\u1ea3o to\u00e0n n\u0103ng l\u01b0\u1ee3ng. V\u1eadn t\u1ed1c pha c\u1ee7a s\u00f3ng thay \u0111\u1ed5i b\u1edfi s\u1ef1 thay \u0111\u1ed5i c\u1ee7a m\u00f4i tr\u01b0\u1eddng. Th\u1ebf nh\u01b0ng kh\u00e1c v\u1edbi v\u1eadn t\u1ed1c, t\u1ea7n s\u1ed1 c\u1ee7a n\u00f3 l\u1ea1i kh\u00f4ng thay \u0111\u1ed5i. \u0110i\u1ec1u n\u00e0y \u0111\u00e3 \u0111\u01b0\u1ee3c quan s\u00e1t k\u1ef9 l\u01b0\u1ee1ng v\u00e0 c\u1ef1c k\u1ef3 r\u00f5 r\u00e0ng khi m\u00e0 s\u00f3ng truy\u1ec1n t\u1eeb m\u00f4i tr\u01b0\u1eddng n\u00e0y sang m\u00f4i tr\u01b0\u1eddng kh\u00e1c. \u0110i\u1ec1u ki\u1ec7n k\u00e8m theo l\u00e0 g\u00f3c t\u1edbi ph\u1ea3i kh\u00e1c g\u00f3c 0 \u0111\u1ed9.<\/p>\n\n\n\n

S\u1ef1 kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng<\/p>\n\n\n\n

V\u1edbi hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng, \u0111\u00e2y l\u00e0 hi\u1ec7n t\u01b0\u1ee3ng quan s\u00e1t th\u01b0\u1eddng g\u1eb7p nh\u1ea5t. B\u1ea5t c\u1ee9 lo\u1ea1i s\u00f3ng n\u00e0o c\u0169ng c\u00f3 th\u1ec3 kh\u00fac x\u1ea1 \u0111\u01b0\u1ee3c khi n\u00f3 t\u01b0\u01a1ng t\u00e1c \u1edf trong m\u00f4i tr\u01b0\u1eddng. C\u00f3 th\u1ec3 th\u1ea5y r\u1eb1ng, khi s\u00f3ng \u00e2m truy\u1ec1n t\u1eeb m\u00f4i tr\u01b0\u1eddng n\u1ecd sang m\u00f4i tr\u01b0\u1eddng kia, c\u00e1c s\u00f3ng n\u01b0\u1edbc s\u1ebd di chuy\u1ec3n \u0111\u01b0\u1ee3c theo m\u1ed9t \u0111\u1ed9 s\u00e2u kh\u00e1c nhau.<\/p>\n\n\n\n

\u0110\u1ecbnh lu\u1eadt Snell \u0111\u00e3 n\u00eau r\u1ea5t r\u00f5 v\u1ec1 c\u00e1c hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 n\u00e0y. \u00d4ng ph\u00e1t bi\u1ec3u ri\u00eang v\u1edbi tr\u01b0\u1eddng h\u1ee3p c\u1eb7p m\u00f4i tr\u01b0\u1eddng, m\u1ed9t s\u00f3ng v\u1edbi m\u1ed9t t\u1ea7n s\u1ed1 duy nh\u1ea5t. L\u00fac n\u00e0y, \u00f4ng cho r\u1eb1ng, t\u1ef7 l\u1ec7 sin c\u1ee7a g\u00f3c t\u1edbi v\u00e0 g\u00f3c kh\u00fac x\u1ea1, s\u1ebd c\u00f3 s\u1ef1 t\u01b0\u01a1ng \u0111\u01b0\u01a1ng v\u1edbi t\u1ef7 s\u1ed1 c\u1ee7a v\u1eadn t\u1ed1c pha b\u00ean trong hai m\u00f4i tr\u01b0\u1eddng. Ngo\u00e0i ra, ch\u00fang c\u00f2n t\u01b0\u01a1ng \u0111\u01b0\u01a1ng v\u1edbi chi\u1ebft su\u1ea5t t\u01b0\u01a1ng \u0111\u1ed1i c\u1ee7a hai m\u00f4i tr\u01b0\u1eddng n\u00e0y.<\/p>\n\n\n\n

T\u1ef7 s\u1ed1 chi\u1ebft su\u1ea5t c\u1ee7a m\u00f4i tr\u01b0\u1eddng<\/p>\n\n\n\n

Ta c\u00f3 i l\u00e0 g\u00f3c gi\u1eefa tia s\u00e1ng, tia \u0111i t\u1eeb m\u00f4i tr\u01b0\u1eddng m\u1ed9t \u0111\u1ebfn m\u1eb7t ph\u1eb3ng ph\u00e2n c\u00e1ch v\u00e0 ph\u00e1p tuy\u1ebfn m\u1eb7t ph\u00e2n c\u00e1ch c\u1ee7a hai m\u00f4i tr\u01b0\u1eddng. C\u00f2n r l\u00e0 g\u00f3c gi\u1eefa tia s\u00e1ng \u0111i t\u1eeb m\u1eb7t ph\u00e2n c\u00e1ch ra \u0111\u1ebfn m\u00f4i tr\u01b0\u1eddng hai v\u1edbi ph\u00e1p tuy\u1ebfn. G\u1ecdi n1 l\u00e0 chi\u1ebft su\u1ea5t c\u1ee7a m\u00f4i tr\u01b0\u1eddng 1, t\u01b0\u01a1ng t\u1ef1 g\u1ecdi n2 l\u00e0 chi\u1ebft su\u1ea5t c\u1ee7a m\u00f4i tr\u01b0\u1eddng 2.<\/p>\n\n\n\n

Ta s\u1ebd c\u00f3 c\u00f4ng th\u1ee9c nh\u01b0 sau: Sin(i)\/Sin(r)=n2\/n1. C\u00f4ng th\u1ee9c n\u00e0y \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng r\u1ea5t nhi\u1ec1u trong b\u00e0i t\u1eadp hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng. Th\u1ebf n\u00ean b\u1ea1n h\u00e3y ghi nh\u1edb k\u1ef9 \u0111\u1ec3 s\u1eed d\u1ee5ng v\u00e0 l\u00e0m b\u00e0i t\u1eadp nh\u00e9.<\/p>\n\n\n\n

T\u1ef7 s\u1ed1 n\u00e0y s\u1ebd kh\u00f4ng thay \u0111\u1ed5i. Ch\u00fang ph\u1ee5 thu\u1ed9c v\u00e0o b\u1ea3n ch\u1ea5t c\u1ee7a hai m\u00f4i tr\u01b0\u1eddng. \u0110\u00e2y \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 chi\u1ebft su\u1ea5t t\u1ec9 \u0111\u1ed1i c\u1ee7a m\u00f4i tr\u01b0\u1eddng ch\u1ee9a tia kh\u00fac x\u1ea1 \u0111\u1ed1i v\u1edbi m\u00f4i tr\u01b0\u1eddng ch\u1ee9a tia t\u1edbi. N\u00f3i c\u00e1ch kh\u00e1c ch\u00ednh l\u00e0 m\u00f4i tr\u01b0\u1eddng 2 so v\u1edbi m\u00f4i tr\u01b0\u1eddng 1. N\u1ebfu nh\u01b0 t\u1ec9 s\u1ed1 n\u00e0y l\u1edbn h\u01a1n 1, ta c\u00f3 th\u1ec3 hi\u1ec3u l\u00e0 g\u00f3c kh\u00fac x\u1ea1 nh\u1ecf h\u01a1n so v\u1edbi g\u00f3c t\u1edbi. \u0110i\u1ec1u n\u00e0y \u0111\u1ed3ng ngh\u0129a v\u1edbi vi\u1ec7c m\u00f4i tr\u01b0\u1eddng 2 chi\u1ebft quang h\u01a1n so v\u1edbi m\u00f4i tr\u01b0\u1eddng 1. C\u00f2n n\u1ebfu nh\u01b0 t\u1ec9 s\u1ed1 n\u00e0y nh\u1ecf h\u01a1n so v\u1edbi 1, ta s\u1ebd nh\u1eadn \u0111\u01b0\u1ee3c \u0111i\u1ec1u ng\u01b0\u1ee3c l\u1ea1i. G\u00f3c kh\u00fac x\u1ea1 s\u1ebd l\u1edbn h\u01a1n so v\u1edbi g\u00f3c t\u1edbi. Khi \u0111\u00f3, m\u00f4i tr\u01b0\u1eddng 2 s\u1ebd chi\u1ebft quang k\u00e9m h\u01a1n so v\u1edbi m\u00f4i tr\u01b0\u1eddng 1.<\/p>\n\n\n\n

H\u00ecnh \u1ea3nh hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng<\/p>\n\n\n\n

M\u1ed9t s\u1ed1 b\u00e0i t\u1eadp v\u1ec1 kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng<\/p>\n\n\n\n

D\u01b0\u1edbi \u0111\u00e2y l\u00e0 b\u00e0i t\u1eadp v\u00e0 m\u1ed9t s\u1ed1 l\u1eddi gi\u1ea3i cho d\u1ea1ng b\u00e0i \u0111\u00f3 \u0111\u1ec3 c\u00e1c b\u1ea1n c\u00f3 th\u1ec3 \u00f4n k\u1ef9 \u0111\u01b0\u1ee3c ki\u1ebfn th\u1ee9c h\u01a1n.<\/p>\n\n\n\n

B\u00e0i 1: Ph\u00e2n bi\u1ec7t c\u00e1c hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng v\u00e0 hi\u1ec7n t\u01b0\u1ee3ng ph\u1ea3n x\u1ea1 \u00e1nh s\u00e1ng.<\/p>\n\n\n\n

B\u00e0i 2: Gi\u1ea3i th\u00edch k\u1ef9 hi\u1ec7n t\u01b0\u1ee3ng \u0111\u01b0\u1ee3c n\u00eau ra d\u01b0\u1edbi \u0111\u00e2y. Khi ta \u0111\u1eb7t m\u1eaft nh\u00ecn d\u1ecdc theo chi\u1ebfc \u0111\u0169a th\u1eb3ng \u0111\u1ea7u ti\u00ean, ta c\u00f3 th\u1ec3 kh\u00f4ng nh\u00ecn \u0111\u01b0\u1ee3c \u1edf \u0111\u1ea7u d\u01b0\u1edbi c\u1ee7a \u0111\u0169a. Ta gi\u1eef nguy\u00ean v\u1ecb tr\u00ed \u0111\u1eb7t m\u1eaft \u0111\u00f3. Sau \u0111\u00f3 \u0111\u1ed5 th\u00eam n\u01b0\u1edbc v\u00e0o b\u00e1t. Li\u1ec7u c\u00f3 nh\u00ecn th\u1ea5y \u0111\u1ea7u d\u01b0\u1edbi c\u1ee7a \u0111\u0169a hay kh\u00f4ng?<\/p>\n\n\n\n

L\u1eddi gi\u1ea3i c\u1ee7a b\u00e0i t\u1eadp<\/p>\n\n\n\n

B\u00e0i 1: Hi\u1ec7n t\u01b0\u1ee3ng ph\u1ea3n x\u1ea1 \u00e1nh s\u00e1ng s\u1ebd c\u00f3 t\u00ednh ch\u1ea5t sau: Khi tia t\u1edbi g\u1eb7p m\u1eb7t ph\u00e2n c\u00e1ch \u1edf hai m\u00f4i tr\u01b0\u1eddng trong su\u1ed1t, ch\u00fang s\u1ebd b\u1ecb h\u1eaft l\u1ea1i m\u00f4i tr\u01b0\u1eddng trong su\u1ed1t c\u0169. Ngo\u00e0i ra, g\u00f3c ph\u1ea3n x\u1ea1 b\u1eb1ng v\u1edbi g\u00f3c t\u1edbi.<\/p>\n\n\n\n

C\u00f2n \u0111\u1ed1i v\u1edbi hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng, tia t\u1edbi kh\u00f4ng b\u1ecb h\u1eaft tr\u1edf l\u1ea1i. Tia t\u1edbi g\u1eb7p m\u1eb7t ph\u00e2n c\u00e1ch \u1edf gi\u1eefa hai m\u00f4i tr\u01b0\u1eddng trong su\u1ed1t. Ch\u00fang b\u1ecb g\u00e3y kh\u00fac t\u1ea1i m\u1eb7t ph\u00e2n c\u00e1ch, sau \u0111\u00f3 ti\u1ebfp t\u1ee5c \u0111i ti\u1ebfp v\u00e0o m\u00f4i tr\u01b0\u1eddng trong su\u1ed1t th\u1ee9 hai. G\u00f3c kh\u00fac x\u1ea1 c\u00f3 gi\u00e1 tr\u1ecb b\u1eb1ng v\u1edbi g\u00f3c t\u1edbi.<\/p>\n\n\n\n

B\u00e0i 2: C\u00f3 th\u1ec3 gi\u1ea3i th\u00edch nh\u01b0 sau:<\/p>\n\n\n\n

Khi ta ch\u01b0a \u0111\u1ed5 n\u01b0\u1edbc v\u00e0o b\u00e1t, ta s\u1ebd kh\u00f4ng nh\u00ecn th\u1ea5y \u0111\u01b0\u1ee3c \u0111\u1ea7u d\u01b0\u1edbi c\u1ee7a chi\u1ebfc \u0111\u0169a. Th\u1ebf nh\u01b0ng trong kh\u00f4ng kh\u00ed, v\u00ec \u00e1nh s\u00e1ng ch\u1ec9 truy\u1ec1n theo \u0111\u01b0\u1eddng th\u1eb3ng t\u1eeb A \u0111\u1ebfn m\u1eaft. Nh\u1eefng \u0111i\u1ec3m \u1edf tr\u00ean chi\u1ebfc \u0111\u0169a th\u1eb3ng \u0111\u00e3 ch\u1eafn \u0111\u01b0\u1ee3c \u0111\u01b0\u1eddng truy\u1ec1n \u0111\u00f3. Th\u1ebf n\u00ean tia s\u00e1ng n\u00e0y kh\u00f4ng th\u1ec3 \u0111\u1ebfn \u0111\u01b0\u1ee3c v\u1edbi m\u1eaft.<\/p>\n\n\n\n

Khi ta gi\u1eef nguy\u00ean v\u1ecb tr\u00ed ta \u0111\u1eb7t m\u1eaft v\u00e0 \u0111\u1eb7t \u0111\u0169a. Khi \u0111\u1ed5 n\u01b0\u1edbc v\u00e0o b\u00e1t t\u1edbi m\u1ed9t v\u1ecb tr\u00ed n\u00e0o \u0111\u00f3, ta c\u00f3 th\u1ec3 l\u1ea1i nh\u00ecn th\u1ea5y \u0111i\u1ec3m c\u0169.<\/p>\n\n\n\n

V\u00ed d\u1ee5 hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng<\/p>\n\n\n\n

Tr\u00ean \u0111\u00e2y l\u00e0 nh\u1eefng th\u00f4ng tin m\u00e0 ch\u00fang t\u00f4i cung c\u1ea5p v\u1ec1 hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1 \u00e1nh s\u00e1ng. Ch\u00fang t\u00f4i tin r\u1eb1ng \u0111\u00e2y l\u00e0 nh\u1eefng chia s\u1ebb c\u1ea7n thi\u1ebft cho con \u0111\u01b0\u1eddng h\u1ecdc v\u1ea5n c\u1ee7a c\u00e1c b\u1ea1n. N\u1ebfu nh\u01b0 b\u1ea1n quan t\u00e2m \u0111\u1ebfn nh\u1eefng b\u00e0i vi\u1ebft kh\u00e1c, h\u00e3y tham kh\u1ea3o ngay nh\u00e9. Tr\u00ean website c\u1ee7a ch\u00fang t\u00f4i c\u00f2n c\u00f3 r\u1ea5t nhi\u1ec1u th\u00f4ng tin th\u00fa v\u1ecb v\u1ec1 h\u00f3a h\u1ecdc, v\u1eadt l\u00fd\u2026 B\u1ea1n c\u00f3 th\u1ec3 t\u00ecm hi\u1ec3u th\u1eed<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"

Ghi ch\u00fa: T\u00e0i li\u1ec7u tr\u00edch d\u1eabn Trong cu\u1ed9c s\u1ed1ng, ch\u1eafc ch\u1eafn s\u1ebd c\u00f3 nhi\u1ec1u l\u00fac c\u00e1c em g\u1eb7p hi\u1ec7n t\u01b0\u1ee3ng kh\u00fac x\u1ea1. V\u00ed d\u1ee5, khi c\u00e1c em \u0111ang khu\u1ea5y m\u1ed9t c\u1ed1c n\u01b0\u1edbc \u0111\u01b0\u1eddng, s\u1eed d\u1ee5ng th\u00eca ho\u1eb7c mu\u1ed7ng khu\u1ea5y, c\u00e1c em s\u1ebd th\u1ea5y \u0111\u01b0\u1ee3c hi\u1ec7n t\u01b0\u1ee3ng n\u00e0y. Qua m\u1eb7t ph\u00e2n c\u00e1ch gi\u1eefa kh\u00f4ng kh\u00ed v\u00e0 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_disable_autopaging":false},"categories":[4,7],"tags":[],"class_list":["post-1179","post","type-post","status-publish","format-standard","hentry","category-trung-hoc","category-vat-ly"],"_links":{"self":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/1179","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/comments?post=1179"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/1179\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=1179"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=1179"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=1179"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}