Question

5. 0/10 points Previous Answers OSCIPhys2016 20.3.P.026. MyN If the 0.150 mm diameter tungsten filament in a light bulb is to have a resistance of 0.100 at 20.0°C, how long (nm) should it be? Xm Additional Materials Reading 6. -/10 points OSColPhys2016 20.3.P.029. My NC (a) To what temperature (°C) must you raise a copper wire, originally at 20.0*, to double its resistance, neglecting any changes in dimensions? (b) Does this happen in household wiring under ordinary arcumstances O Yes No Additional Materials Reading Submit Answer Practice Arother Version

Answer 1

r = 0.15 x 103 m 2 - radius R=o.ls & Resistance Tref = 20°c l= ? Resistivity of tungsten at 20°c f = 5.6*108 am Now, Rull Ty2 - - TRY? - 3.14 x Orlx. 03) 5.68108 O 021

- T=? , Tref = 20°c we know, Az Reef [ 1 + x (T- Pred) Rug - Reef [ 1+ 4 (AT) J 2 = 1 + AT & AT= 7 AT = 2 -) -) Now, u = 3.9x10-3 / °c 2) AT = 3.9810²3 (AT= 256.41 ocl rise in temperature for resistance to become twice that of the original

② No, resistancer hauge In every day wiring the current needs to be very tigh if we want want to change as to a a R Ruf [ 1 + 2 AT] as a in generally low - Change in resistance n.