In: Physics
A wire made from tungsten is 4.5 m long and 0.45 mm in diameter. What is its resistance at 1500°C?
Length of the tungsten wire l = 4.5 meters
Diameter of the tungsten wire d = 0.45 mm or 0.00045 meters
Resistivity of of tungdten wire at 15000 C = 40.36
10 - 6 ohm-cm OR O.4036
10 - 6 ohm-meter
Resistance R =
(
l / A )
where ,
= resistivity of the wire in ohm-meter
l = length of the wire in meters
A = Area of the wire in meter2
=
/ 4
(diameter)2
=
/ 4
( 0.00045 )2
= 1.59
10 - 7 m2
R =
(
l / A )
= O.4036
10 - 6
( 4.5 / 1.59
10 - 7)
= 11.423 Ohms
Resistance of the tungsten wire at 1500o C R = 11.423 Ohms