Question

1 小明注意到家中的灯泡比平常亮,猜测电压可能超过了220V 他做了如下实验 关闭家中他电路 只开一只 220V 100

Answer 1

1

R=Uo^2/Po=220^2/100=484Ω

W=(121/3000)Kwh=(121/3000)*(3.6*10^6)J=1.452*10^5J

W=(U^2/R)*t

U=√{WR/t}=√{1.452*10^5*484/(20*60)}=242V

R'=U'/I=(U-Uo)/(Po/Uo)=(242-220)/(100/220)=48.4Ω

2

U1=I1*R

U2=I2*R

U2-U1=(I2-I1)*R

R=(U2-U1)/(I2-I1)=(10-8)/0.2=10Ω

P2-P1

=U2^2/R-U1^2/R

=100/10-64/10

=10-6.4

=3.6W