9 V battery is connected to wire made up of three segments of different materials connected in a series: 10 cm copper, then 12 cm iron, then 18 cm tungsten. All wires are 0.26 mm diameter. Find potential difference across each wire.

Constants:

p Copper= 1.7 x 10-8

p Iron = 9.7 x 10 -8

p Tungsten = 5.6 x 10-8

26 mm diameter = 0.13 mm radius or 1.3 x 10-4 m

**2. Relevant equations**

R=pl/A

area of wire (1.3 x 10-4)(1.3 x 10-4) x pi = 5.31 x 10-8 meters squared

**3. The attempt at a solution**

Copper Resistance

R=pl/a

R= (1.7 x 10-8 ohm m)(.1m)/5.31 x 10-8 meters squared

R=0.032 ohm

Iron Resistance

R=pl/a

R=(9.7 x 10-8 ohm m)(.12m)/5.31 x 10-8 meters squared

R=0.22 ohm

Tungsten Resistance

R=pl/a

R=(5.6 x 10-8 ohm m)(0.18 m)/5.31 x 10-8 meters squared

R=0.19

R total series = r1 + r2 + r3

= .032 + .22 + .19

= 0.442 ohm

V copper = vtotal * Rcopper/R total

= 9 V * .032/.442

= 0.65 V

V silver = vtotal *Rsilver/R total

=9 V * .22/.442

=4.48 V

V Tungsten = vtotal * Rtungsten/R total

=9V *.387/.442

= 3.87 V

Volts all add up to 9 so 2nd Law is good but my answers are wrong somewhere...

Thanks,

Scott