Cdu 25: H i e u d i e n t h e giffa ano't v a cato't cua m o t o'ng Rornghen l a U = k V Coi v a n toe ban d a u cua chum electron (electron) p h a t r a ttf catot b k n g k h o n g B i e t h a n g so P l a n g h = 6,625.10~^^J.s, d i e n t i c h nguyen to b a n g 1,6.10'^^C T a n so Idm n h a t cua t i a Rornghen ong c6 the p h a t r a l a : D 60,380.10'^Hz C 6,038.10^^Hz B 60,380.10^^Hz A 6,038.10^^Hz ' Giai PT J Ta c6: e U = h f = > f = — = 6,038.10"HZ h Vdy chgn dap an A Cdu 26: M o t k h u n g d a y d a n h i n h chOr n h a t c6 100 vong, d i e n t i c h moi vong 600 cm^, quay deu quanh true doi xufng cua k h u n g vdfi v a n toe goe 120 vong/phut t r o n g m o t tCf truf&ng deu eo cam ufng ttf bang 0,2T True quay vuong goe v d i cac dUorng cam ufng tCr Chon goe thori gian la lue vectof phap t u y e n cua m a t phSng k h u n g d a y ngUtfc hifdfng vdfi vector cam ufng tii B i e u thufc suat d i e n dong cam ufng t r o n g k h u n g l a : A e = 4,8;isin ; r t - - ( V ) C e = 4871 B e = 487tsin(4;rt + n ) ( V ) sin r t - - ( V ) D e = 4,87isin(407rt + i ) ( V ) Giai Theo de b a i , t a c6: + D i e n t i c h v o n g day: S = 600cm^ = 6.10"^m^ + So v o n g day: N = 100 vong •f C a m ufng tCr: B = 0,2T + Tdc quay cua roto: 120 vong/phut = vong/giay Vao thcfi d i e m t = 0, goe giffa phap t u y e n cua k h u n g day va cam ufng tff l a a = 71 Ta C O tCf t h o n g qua m o t vong day l a : cp, = BScos(a + 7r) = BScos(27rnt + 7r) V i k h u n g day c6 N vong giong n e n t r o n g k h u n g c6 suat dien dong: e = - ^ = NBS27msin(27mt + r ) N T h a y so t a c6: e = 4,87isin(407rt + i ) ( V ) Vdy chgn dap an D 12 Giai Chi ti^t dS thi T S DH, C D M6n V^t If