Question

A Nichrome heating element that has resistance 28.0 Ω is connected to a battery that has emf 86.0 V and internal resistance 1.6 Ω . An aluminum cup with mass 0.130 kg contains 0.200 kg of water. The heating element is placed in the water and the electrical energy dissipated in the resistance of the heating element all goes into the cup and water. The element itself has very small mass. How much time does it take for the temperature of the cup and water to rise from 21.2 ∘C to 34.5 ∘C? (The change of the resistance of the Nichrome due to its temperature change can be neglected.)

Answer 1

e emf of battery = e = 8610v internal resistance of battery = r - hon resistence of Aléchrome heating element = R = 28- mass of aluminum cup = m = 0.130 kg = 130g mass of wates in cup - mw = 0.2000 kg = 200g specifice heat of aluminum= SA= 0.g J1g-k specific heat of wafes - Sw= 4.186 Jlgk change in temperature - DT - 34.5°C-21-2 °C = 13.30 of cup and water ST = 13.3K eroc Let t' is the time faren fors the process. current in Nichrome heating elementi e -A= 8.6 RAR A = 2,914 28+16 cup & head gashed by weater. No er Heat supplied by Nichrome - heat gained heating element Rt & MASART &mw SWAT t = MASA AT + MW SWAT - 2 R a t = 130x0.9 X 13:3+200 x 4.1864 13:3 Seconds (2.91) 2 x 28 53.52 seconds =