Positive SSL
A 52V
B 5V
C 53V
D 6V

有效值 = 均方根值

先平方 再 平均 再 開平方根

波形平方並不好算,可以用有效值反推回去,觀念如下:

`有效值= sqrt((波形平方和)/(週期T)`

`有效值^2 = (波形平方和)/T`

`有效值^2xxT = 波形平方和`

該波形有效值算法如下:`V_(rms)` = `sqrt((((10)/(sqrt3))^2*3+10^2*1+((10)/(sqrt2))^2*2)/6)`

= `sqrt(50)` = `5sqrt2(V)`


A –0.6
B 0
C 0.75
D 1

交直流混合波是一交流波形含有直流成份

直流成份的直流值 VDC = `-3`

交流波形的有效值 Vrms = `(4sqrt(2))/sqrt(2)`

交直流混合波的有效值 = `sqrt((V_(DC))^2+(Vrms)^2)`

= `sqrt(3^2+((4sqrt(2))/sqrt(2))^2)`

= `sqrt(9+16)` = 5

交直流混合波的直流值 = 直流值 VDC = `-3V`

`-3/5 = - 0.6 `


A A的電壓頻率較B高
B A輸出的平均功率較B高
C A的平均值電壓較B高
D A的有效值電壓較B高

A 頻率50Hz、B 頻率`50/(2π)=7.95Hz`

算功率要用有效值(不是平均值)

`V_(A(rms))=sqrt(5^2*64/100)= 4V`

`P_A=4^2/100=0.16W`

`V_(B(rms))=5/sqrt(2)=3.53V`

`P_B=(5/sqrt(2))^2/50=0.25W`

`V_(A(DC))=5*0.64=3.2V`

`V_(B(DC))=5*0.636=3.18V`


A 110sin(60t)
B 110sin(60πt)
C 1102sin(60πt)
D 1102sin(120πt)

正弦波瞬時電壓表示式: `v(t)=V_msin(ωt)`

`V_(rms)=110V ;V_m = 110sqrt(2)V`

`f=60Hz`; `ω = 2πf` `= 2*60*π` `= 120π`

`V_(t)=110sqrt(2) sin(120πt)`


A 11.66V
B 10.66V
C 6.66V
D 5.66V

sinθ最大值=1

v(t) 最大值 = `v(t)= 4sqrt(2) + 6 =11.656V`


A v(t)=20sin(377t)V
B v(t)=17.3sin(377t)V
C v(t)=14.4sin(377t)V
D v(t)=10sin(377t)V

30° 60° 90°三角形比例`1:sqrt(3):2`,由圖可知,v(t)角度 0°,大小 `5sqrt(3)*2` =`10sqrt(3)` = 17.3V; `v(t)= 17.3sin(377t)(V)`


A 20%
B 40%
C 60%
D 80%

設週期為1

正峰值的時間 = Ton,所以負峰值的時間為 1-Ton

電壓平均值 = `(10*T_(on)+(-5)*(1-T_(on)))/1` = 1

Ton = 0.4

工作週期 = `T_(on)/T*100%` = `0.4/1*100%` `=40%`


A 55V
B 552V
C 110V
D 1102V

`v(t)=110sqrt(2)sin(377t+30°)V`

`v(t)=110sqrt(2)sin(120πt+30°) V`

`v(1/30)` `=110sqrt(2)sin(120π1/30+30°) V`

`=110sqrt(2)sin(4π+30°) V`

`=110sqrt(2)(1/2)V`

`=55sqrt(2) (V)`


A 1V
B 1.5V
C 2V
D 3V

`V_(DC)` = `(3*2+(-1)*1+5*1+(-2)*2)/6` = `1V`


A 26V
B 26/3V
C 3V
D 2V
`V_(rms)` = `sqrt((3^2*2+(-1)^2*1+5^2*1+(-2)^2*2)/6)` = `sqrt(26/3)V`