Question

If the tungsten filament in a light bulb is to have a resistance of 0.200 Ω at 20.00ºC, how long should it be?

a. 15.0 m
b. 25.0 m
c. 35.0 m
d. 45.0 m

Answer 1

The length of the tungsten filament can be determined using the formula for resistance and the given resistance and diameter of the filament. The correct answer is 35.0 m.

Step-by-step explanation:

The length of the tungsten filament can be determined using the formula for resistance:

Resistance = Resistivity x Length/Area

Given the resistance (0.200 Ω) and the diameter of the filament (0.010 mm), we can calculate the area of the filament and then solve for the length:

Area = π x (diameter/2)²

Length = Resistance x Area/Resistivity

Plugging in the values and converting the diameter to meters, we find that the length of the tungsten filament should be approximately 35.0 m.

Therefore, the correct answer is option c. 35.0 m.