A common flashlight bulb is rated at 0.30 A and 2.8 V (the values of the current

Question

A common flashlight bulb is rated at 0.30 A and 2.8 V (the values of the current and voltage under operating conditions). If the resistance of the tungsten bulb filament at room temperature (20°C) is 1.7 , what is the temperature of the filament when the bulb is on?
A common flashlight bulb is rated at 0.30 A and 2.8 V (the values of the current and voltage under operating conditions). If the resistance of the tungsten bulb filament at room temperature (20°C) is 1.7 , what is the temperature of the filament when the bulb is on?
A common flashlight bulb is rated at 0.30 A and 2.8 V (the values of the current and voltage under operating conditions). If the resistance of the tungsten bulb filament at room temperature (20°C) is 1.7 , what is the temperature of the filament when the bulb is on?

Explanation / Answer

from the ohm's law

V = IR

R= V/I

=2.8 V/0.30 A

=9.33 ohm

rletaion between reistance and temperature is

R = R0 + alpha*(T - T0)

9.33=1.7 +4.5 * 10^-3 T- (20+273) * 4.5 * 10^-3

T = 1988.55 K or 1988.55 K -273 = 1715.55 C

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