Question

Two resistors of resistances R 1 = 100+/- 3 ohm and R2= 200 +/- 4 ohm are connected (a) in series, (b) in parallel. Find the equivalent resistance of the (a) series combination, (b) parallel combination. Use for (a) the realtion R = R1+ R2and for (b) 1/R ' = 1/R1+ 1/R2and ΔR '/R '2= ΔR1/R1 2+ ΔR2/R2 2.

Answer 1

a.

R= R1+R2

= 100/3 + 200/4

=(400+600)/12

=1000/12

=83.4 ohm.

b.

R= 1/R1+1/R2

=3/100+ 4/200

=(6+4)/200

=10/200

=0.05 ohm