电工学PPT习题参考答案.pdf

习题1参考答案

1-1(a)21V;(b)-6V;(C)2A;(D)-1.5A

1-2(1)-10V(2)b点电位高

1-3Plov=-10W(发出),Pia=5W(吸收),P?A=5W(吸收)

1-4图(a):i=1A,V?=2V,Vb=0V,Ve=-3V;

图(b):i=-1A,Va=-5V,Vb=-3V,Ve=0V

1-5u=-9000;

-6c10!-12x10

1-6a)7V;b)2V

1-7I=0.4A;Ua=0V;Uah=10V

1-8(a)U=U?-IR;(b)U=U?+IR

1-96.4V

1-1012V,2Ω串联

1-114A,6Ω并联

1-122A;24.5Ω;50V;100A

习题2参考答案

2-1Ra=42

2-25Ω

2-5P=1W

2-6U=6.67V

2-7I=3A

28i=号A

2-9ii=-1A,iz=2A,i?=4A

2-10=10V

2-11

}A、0A、-号A、A、5A、v

2-12ii=3A、iz=1A、i3=4A

2-13is=4A

2-16I=12.5A

2-17U=12V

2-181=0A

2-19答案：I=-1A

习题3参考答案

参考答案

3-12V,-4.5A

3-3(a)1.5A,3A;(b)6A,OA

3-41c=30e-1??1v,ic=3e1A

3-52002

3-6“.=5e2WV,i=-e2SJA

3-8“c=10(1-e*)V

3-93.72A

3-1040KV

3-11

it=t(2)d-e÷)=3(I-e)A

3-1212+6e?25V

3-1310A,12A,0.1s

3-14Uc=(18+36e20I)V

3-15i?=(5-2e2)A

习题4参考答案

4-1(1)i=620°A

(2)i?=2Asa°A

4-2(1)u=127sin(314r+30)V

(2)u=220√2sin(314r+45°)V

(3)i=5√2sin(314r+36.9°)A

(4)i=2sin(314/+90)A

4-3有效值U?=220V,初相位φ=135°;

有效值U?=√,初相位m=30

相位差q?=135-30=105°

4-4(1)R=5Q,X=0,电路为电阻性电路，电压与电流的相位差φ=0

的相位差φ=-50

(3)R=62,X=8,电路为感性电路，电压与电流的相位差φ,=53.1°

4-5=220√2sin(314t+90°)V;U?=220190°V

u?=220sin(314r-30)V;U?=110√Z∠30°V

i=10√2sin314rA;i=10l0°A

4-6(a)U,=50V

(b)U,=30√2v

4-7R=202

L=1.19mH

4-8Z=4.47104Ω,i?=2∠369A,i?=U53.1A

4-9i=10√2145°A,U,=10010A

4-10U=√2∠45°V

4-11Z=8603°2,1=27.5∠63.5°A,P=3630W

4-12R=20Ω,X?=51.2Ω,Xc=6.2Ω

4-13i?=10290°A,i?=10∠53.1A,i=13.4∠26.6°A

5=0.6:λ=0.89

4-14cosφ=0.8,R=82,L=19.1mH

4-15l=263A,S=100kVA,Q=80kvar

4-16R=10Ω,Q=4kvar

习题5参考答案

5-1(1)负载星形连接：U。=220V,I,=44A

(2)负载三角形连接：U。=380V,I?=131.63A

5-2=√3e-jwA

5-3L=220/0*V,U=220∠120°V,L=22Y120°V

A=22∠30°A,=22∠150°A,尽=2Y90°A

A=38L60°A,=38∠180°A,=38160°A

5-6P=6.63kW

5-8A1的示数为BA