Anonymous

R = 1/(1/x + 1/(2x) + 1/(4x)) = 4x/7; x = 5; R = 20/7

Anonymous

Re = 1/(1/5+1/10+1/20) = 2.857 ohm or 5//10 = 5*10/15 = 10/3 10/3 // 20 = 200/3 / (20+10/3) = 200/3 /70/3 = 200/70 = 20/7 = 2.857 ohm

Anonymous

Since they are in parallel, they all share the same voltage V and we can find the current through each: V/5+V/10+V/20 = V(4/20+2/20+1/20) = V/(20/7) = V*(0.35) so 1/Req = 0.35 mhos OR Req = 1/0.35 or about 2.86Ω

Anonymous

1/R = (1/5) + (1/10) + (1/20) 1/R = 0.2 + 0.1 + 0.05 1/R = 0.35 R = 1/0.35 = 2.86 Ω alternate method, do two at a time. Ra = 10*20/(10+20) = 200/30 = 6.67 R = 6.67*5/(5+6.67) = 33.33/11.67 = 2.86 Ω

Anonymous

lol isn't Rt = ∑ R so Rt = R1 + R2 + R3