C\u00e2u 2 (trang 82 sgk V\u1eadt L\u00ed 12 n\u00e2ng cao):<\/b>\u00a0Ph\u00e1t bi\u1ec3u \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 c\u00f3 s\u00f3ng d\u1eebng n\u00ean m\u1ed9t s\u1ee3i d\u00e2y \u0111\u00e0n h\u1ed3i trong hai tr\u01b0\u1eddng h\u1ee3p:<\/span><\/p>\na) D\u00e2y c\u00f3 m\u1ed9t d\u1ea7u c\u1ed1 \u0111\u1ecbnh, m\u1ed9t \u0111\u1ea7u t\u1ef1 do.<\/p>\n
b) D\u00e2y c\u00f3 hai \u0111\u1ea7u c\u1ed1 \u0111\u1ecbnh.<\/p>\n
L\u1eddi gi\u1ea3i:<\/b><\/p>\n
\u0110i\u1ec1u ki\u1ec7n \u0111\u1ec3 s\u00f3ng d\u1eebng tr\u00ean m\u1ed9t s\u1ee3i d\u00e2y d\u00e0n h\u1ed3i<\/p>\n
N\u1ebfu l \u0111\u1ea7u d\u00e2y c\u1ed1 \u0111\u1ecbnh, l \u0111\u1ea7u d\u00e2y t\u1ef1 do, chi\u1ec1u d\u00e0i d\u00e2y l khi c\u00f3 s\u00f3ng d\u1eebng l\u00e0:<\/p>\n
l = k(\u03b1\/2) = \u03b1\/4 (k = 0,1, 2 …)<\/p>\n
N\u1ebfu hai \u0111\u1ea7u d\u00e2y c\u1ed1 \u0111\u1ecbnh, chi\u1ec1u d\u00e0i d\u00e2y l khi c\u00f3 s\u00f3ng d\u1eebng ph\u1ea3i th\u1ecfa m\u00e3n l\u00e0:<\/p>\n
l = k(\u03b1\/2) (k = 1,2,3 …)<\/p>\n
B\u00c0I T\u1eacP<\/strong><\/p>\nB\u00e0i 1 (trang 83 sgk V\u1eadt L\u00ed 12 n\u00e2ng cao):<\/b>\u00a0Ta quan s\u00e1t thay hi\u1ec7n t\u01b0\u1ee3ng g\u00ec tr\u00ean m\u1ed9t s\u1ee3i d\u00e2y c\u00f3 s\u00f3ng d\u1eebng?<\/span><\/p>\nA. T\u1ea5t c\u1ea3 c\u00e1c ph\u1ea9n t\u1eed c\u1ee7a d\u00e2y tr\u00ean \u0111\u1ec1u \u0111\u1ee9ng y\u00ean.<\/p>\n
B. Tr\u00ean \u0111\u00e2y c\u00f3 nh\u1eefng b\u1ee5ng s\u00f3ng xen k\u1ebd n\u00fat s\u00f3ng.<\/p>\n
C. T\u1ea5t c\u1ea3 c\u00e1c \u0111i\u1ec3m tr\u00ean d\u00e2y \u0111\u1ec1u dao \u0111\u1ed9ng v\u1edbi bi\u00ean \u0111\u1ed9 c\u1ef1 \u0111\u1ea1i.<\/p>\n
D. T\u1ea5t c\u1ea3 c\u00e1c \u0111i\u1ec3m tr\u00ean d\u00e2y \u0111\u1ec1u chuy\u1ec3n \u0111\u1ed9ng v\u1edbi c\u00f9ng v\u1eadn t\u1ed1c.<\/p>\n
L\u1eddi gi\u1ea3i:<\/b><\/p>\n
Ch\u1ecdn B<\/p>\n
B\u00e0i 2 (trang 83 sgk V\u1eadt L\u00ed 12 n\u00e2ng cao):<\/b>\u00a0S\u00f3ng truy\u1ec1n tr\u00ean m\u1ed9t s\u1ee3i d\u00e2y hai \u0111\u1ea7u c\u1ed1 \u0111\u1ecbnh c\u00f3 b\u01b0\u1edbc s\u00f3ng \u03b3. Mu\u1ed1n c\u00f3 s\u00f3ng d\u1eebng tr\u00ean d\u00e2y th\u00ec chi\u1ec1u d\u00e0i l c\u1ee7a d\u00e2y phai th\u1ecfa m\u00e3n \u0111i\u1ec1n ki\u1ec7n.<\/span><\/p>\nA. l = \u03b3\/4;\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 B. l = \u03b3\/2<\/p>\n
C. 2\/3\u03b3;\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 D. l = \u03b32<\/sup><\/p>\nL\u1eddi gi\u1ea3i:<\/b><\/p>\n
Ch\u1ecdn B.<\/p>\n
B\u00e0i 3 (trang 83 sgk V\u1eadt L\u00ed 12 n\u00e2ng cao):<\/b>\u00a0Tr\u00ean m\u1ed9t s\u1ee3 d\u00e2y d\u00e0i 40 cm c\u00f3 s\u00f3ng d\u1eebng, ng\u01b0\u1eddi ta quan s\u00e1t th\u1ea5y c\u00f3 4 b\u1ee5ng s\u00f3ng. T\u1ea7n s\u1ed1 dao \u0111\u1ed9ng l\u00e0 400 Hz. T\u00ecm t\u1ed1c \u0111\u1ed9 truy\u1ec1n s\u00f3ng tr\u00ean d\u00e2y.<\/span><\/p>\nL\u1eddi gi\u1ea3i:<\/b><\/p>\n
Ta c\u00f3 4 b\u1ee5ng s\u00f3ng \u21d2 \u03b1\/2 = 40\/4 = 10 cm \u21d4 \u03b1 = 20cm = 0,2m<\/p>\n
T\u1ed1c \u0111\u1ed9 truy\u1ec1n s\u00f3ng tr\u00ean \u0111\u00e2y: v = \u03b1f = 0,2.400 = 80m\/s\\<\/p>\n
B\u00e0i 4 (trang 83 sgk V\u1eadt L\u00ed 12 n\u00e2ng cao):<\/b>\u00a0M\u1ed9t d\u00e2y c\u00f3 nhi\u1ec1u \u0111\u1ea7u b\u1ecb k\u1eb9p ch\u1eb7t, \u0111\u1ea7u kia bu\u1ed9c v\u00e0o m\u1ed9t nh\u00e1nh c\u1ee7a m\u1ed9t \u00e2m thoa c\u00f3 t\u1ea7n s\u1ed1 600 Hz. \u00c2m thoa dao \u0111\u1ed9ng t\u1ea1o ra m\u1ed9t s\u00f3ng d\u1eebng c\u00f3 4 b\u1ee5ng s\u00f3ng. T\u1ed1c \u0111\u1ed9 s\u00f3ng truy\u1ec1n tr\u00ean d\u00e2y l\u00e0 400 m\/s. T\u00ecm:<\/span><\/p>\na) B\u01b0\u1edbc s\u00f3ng<\/p>\n
b) Chi\u1ec1u d\u00e0i c\u1ee7a d\u00e2y<\/p>\n
L\u1eddi gi\u1ea3i:<\/b><\/p>\n
a) B\u01b0\u1edbc s\u00f3ng \u0111\u01b0\u1ee3c t\u00ednh theo c\u00f4ng th\u1ee9c:<\/p>\n
\u03b1 = vT = v\/f = 400\/600 = 2\/3 m<\/p>\n
b) Chi\u1ec1u d\u00e0i c\u1ee7a d\u00e2y l\u00e0 m\u1ed9t s\u1ed1 nguy\u00ean l\u1ea7n n\u1eefa b\u01b0\u1edbc s\u00f3ng:<\/p>\n
L = k(\u03b1\/2)<\/p>\n
c) Khi c\u00f3 s\u00f3ng d\u1eebng tr\u00ean d\u00e2y c\u00f3 4 b\u1ee5ng, v\u1eady c\u00f3 chi\u1ec1u d\u00e0i l\u00e0:<\/p>\n
L = 4(\u03b1\/2) = 2\u03b1 = 2.2\/3 = 1,33m<\/p>\n
\n
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\n
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C\u00c2U H\u1eceI C\u00e2u 1 (trang 82 sgk V\u1eadt L\u00ed 12 n\u00e2ng cao):\u00a0H\u00e3y v\u1eadn d\u1ee5ng ph\u01b0\u01a1ng tr\u00ecnh s\u00f3ng \u0111\u1ec3 gi\u1ea3i th\u00edch hi\u1ec7n t\u01b0\u1ee3ng s\u00f3ng d\u1eebng tr\u00ean d\u00e2y \u0111\u00e0n h\u1ed3i hai \u0111\u1ea7u c\u1ed1 \u0111\u1ecbnh. L\u1eddi gi\u1ea3i: Theo ph\u01b0\u01a1ng tr\u00ecnh s\u00f3ng ta c\u00f3 bi\u00ean \u0111\u1ed9 s\u00f3ng d\u1eebng c\u00f3 bi\u1ec3u th\u1ee9c: C\u00e1c n\u00fat \u1ee9ng v\u1edbi: C\u00e1c b\u1ee5ng b\u1ee5ng v\u1edbi: […]<\/p>\n","protected":false},"author":3,"featured_media":25165,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false,"tdm_status":"","tdm_grid_status":""},"categories":[1304],"tags":[1434,1433],"yoast_head":"\n
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