Question

Class 10 science board question​

Answer 1

heya ,

(a) as we know that in paraller combination current is divided

I=I1+I2+I3

by ohm law

I=V/RP(RP=effective)

I1=V/R1

I2=V/R2

I3=V/R3

so

V/RP=V/R1+V/R2+V/R3

V/RP=V(1/R1+1/R2+1/R3)

1/RP=1/R1+1/R2+1/R3

This is the expression for paraller

and for series

V=V1+V2+V3

so IRS=IR1+IR2+IR3

RS=R1+R2+R3

this is for series

(b)minimum resistance come when resistance is connected in paraller
so if 12ohm and 12ohm are in paraller therefore effective will be 144/24=6ohm
so power is v²/R= 9/6=1.5

similarly highest is when connected in series find effective and then put in same formula and find ratio of P1 and p2

hope it helps

Answer 2

here is my notes but it's in hindi