一根电热丝通电后15分钟可烧开一壶水,另一根电阻丝接到同一电源上需30分钟烧同样一壶水,若把这两跟电阻丝串联起来接到这个电源上,烧开同样一壶水需要多少分钟?
UI1t1=UIt2
tI=15min=900s t2=30min=1800s
I1/I2=2/1
R1/R2=1/2
串联起来R总=R1+R2=3/2R1
I实=3U/2R=3I1/2
UI1t1=UI实t实
t实=I1t1/I实=I1t1/(3I1/2)
=45/2min=22.5min
并联呢?同理 一根电热丝通电后15分钟可烧开一壶水,另一根电阻丝接到同一电源上需30分钟烧同样一壶水,若把这两跟电阻丝串联起来接到这个电源上,烧开同样一壶水需要多少分钟?
UI1t1=UIt2
tI=15min=900s t2=30min=1800s
I1/I2=2/1
R1/R2=1/2
串联起来R总=R1+R2=3/2R1
I实=3U/2R=3I1/2
UI1t1=UI实t实
t实=I1t1/I实=I1t1/(3I1/2)
=45/2min=22.5min
并联呢?同理