An incandescent light bulb uses a coiled filament of tungsten that is 580 long with a diameter of 46.0 μmμm. At 20.0∘C∘C tungsten has a resistivity of 5.25×10−8Ω⋅m5.25×10−8Ω⋅m. Its temperature coefficient of resistivity is 0.0045 (C∘)−1(C∘)−1, and this remains accurate even at high temperatures. The temperature of the filament increases linearly with current, from 20∘C∘C when no current flows to 2520∘C∘C at 1.00 AA of current. 1. What is the resistance of the light bulb at 20∘C∘C?
2. What is the current through the light bulb when the potential difference across its terminals is 120 VV? (Hint: First determine the temperature as a function of the current; then use this to determine the resistance as a function of the current. Substitute this result into the equation V=IRV=IR and solve for the current II.)
Express your answer to two significant figures and include the appropriate units.
3. What is the resistance when the potential is 120 VV?
Express your answer to two significant figures and include the appropriate units.
4. How much energy does the light bulb dissipate in 1 minmin when 120 VV is supplied across its terminals?
Express your answer in kilojoules to two significant figures.
5. How much energy does the light bulb dissipate in 1 minmin when half that voltage is supplied?
Express your answer in kilojoules to two significant figures.