A common flashlight bulb is rated at 0.23 a and 2.9 v (the values of the current and voltage under operating conditions). if the resistance of the bulb filament at room temperature (20°c) is 1.1 ω, what is the temperature of the filament when the bulb is on? the temperature coefficient of resistivity is 4.3 * 10-3 k-1 for the filament material.

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Physics

Delilah Sanders

29 October, 19:05

A common flashlight bulb is rated at 0.23 a and 2.9 v (the values of the current and voltage under operating conditions). if the resistance of the bulb filament at room temperature (20°c) is 1.1 ω, what is the temperature of the filament when the bulb is on? the temperature coefficient of resistivity is 4.3 * 10-3 k-1 for the filament material.

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Angel Strickland · Answer 1

The resistance at operating temperature is R = V/I = 2.9 V / 0.23A = 12.61 ohmsT from R - R0 = Roalpha (T - T0), we find that:T = T0 + 1/alpha (R/R0 - 1) = 20 degrees Celsius + (1 / 4.3 x 10^-3/K) (12.61 ohms / 1.1 ohms - 1) T = 2453.40 degrees Celsius