. A 0,6 B 0,866 C 0,8 D 0,
A,P= 180(VV) B.P =0 (W) C P= 100(W) D P= 150(W)
'Phdn tich m hu&ng ddn gidi
Ta CO cuong do dong diC>n va hi?u di^n the'hi^u dung ciia m^ch '
^/2 . . . Un IOOV2 Do lech pha giua u voi i : (p = (Py -(p; = Cong sua't tieu thu cua doan mach la:
7t _ Tt ' 3 6 P = U.I.cos(p = 100.1. cos Chpn dap an B 71 I ' 1 ) = 0 347
Cau 2: Cho dogn mach xoay chieu khong phan nhanh. Di?n tro R = 50(Q). Mot cuQn day thuan cam L = i ( H ) va ty bien doi C = ^ ( F ) • Hi^u di?n the hai dau mach: U^B = 220N/2 cos
A . P = 130,8(W)
lOOTrt--
4J (V). Tinh cong suat toan mach? B.P = 143,2{W) C.P = 100(W) D.P = 150,5(W)
<Phdn tick vd huorng dan gidi
1
Cam khang ciia cugn day: Z^=aL = IOOTI.- = 100 Q
Dung khang ciia tu:
10071. 10 ,-3
- = 220Q 227t
Tong tro: Z^^ = ^{Z^-Z^f = ^50^ + (lOO-22of = 130(Q)
Cong suat toan mach: P = RI^ = R = 50. r220^
[isoj = 143,2W.
Chpn dap an B
Cau 3: Mach di^n xoay chieu RLC ghep noi tiep, dat vao hai dau mach mot di$n ap u = Uocoscot (V). Dieu chinh C = Ci thi cong suat ciia mach dat gia tri
cue dai Pmax = 600W. Dieu chinh C = C2 thi h | so cong suat ciia mach la ^ Cong suat ciia m^ch khi do la
A.550W B.250W C. 450W D. 350W
^hdn tich i?d hic&ng ddn gidi
Khi C = Ci thi cong suat ciia mach dat gia trj eye dai nen liic nay trong mach xay ra cpng huong.
> p = i l - = 400 =>U2 = 400R = const max
Khi C = C2 thi h^ so cong suat ciia mach la
COS(p2 = R
^ R 2 + ( Z L - Z C 2 ) ' ^
^0,75. R 2 + ( Z L - Z C 2 ) ' = R^
0,75 3
Cong suat tieu thu ciia mach trong truong hop nay:
P 2 = R . l 2 = R . — ^ R 2 + ( Z L - Z C J 2 _ 600R 600 = R- = = 450W. 2 4 3" 3 ^ Chpn dap an C (adsbygoogle = window.adsbygoogle || []).push({});
C3u 4: Di^n ap hai dau mach RLC mac noi tiep c6 dang: u=200\/2.oos(27tf.t)(V),
(biet cupn day thuan cam) va L, C, co c6' dinh. Dieu chinh bien tro khi R = 50Q
thi gia trj eye dai ciia cong suat la: r, i ur^'