K h i g i a m h6t cuon thuT K h i t a n g cuon cap n vong t a c6: thuf N U '— = — N2-n U cap n vong t a c6: N •— = (2) U (3) — - N2+n ( J Tii (2) va (3) suy r a : =2« N, + n = - 2n Nj - n =^3n = N , ^ n = ^ (4) , K h i t a n g cuon thuf cap t h e m 3n vong t a c6: ' TCf(l)va(5)tac6: - ^ = ^ U =200(V) 100 ^ ^ Vdy chgn dap an B Cdu 13: T r o n g t h l n g h i e m Y - a n g ve giao thoa a n h sang, nguon sang phat dong thori h a i buTc xa don sic, t r o n g bufc xa m a u c6 budc song 720 n m va bufc xa mau luc c6 hil6c song X (c6 gia t r i t r o n g khoang tii 500 n m den 575 n m ) T r e n m a n quan sat, giijfa h a i v a n sang gan n h a t va cung mau vdri v a n sang t r u n g t d m c6 v a n sang mau luc Gia t r i cua X l a : A 500 n m B 520 n m C 540 n m D 560 n m Giai T a i v i t r i c6 h a i v a n sang t r u n g va c6 m a u t r u n g vdi v a n trung t a m t a c6: k,X^^k^l,=k,X (1) Giufa v a n t r u n g t a m va v a n gan n h a t p h a i c6 v a n m a u luc n e n k cua mau luc p h a i l a k = Tii t a c6: k^X^ = 9X 9X Suy r a : k, = — X^ V i 500nm