Question

Use the DC Construction kit to build a simple circuit to perform the following task:

You are asked to use a single resistor and a 110 V DC battery for the purpose of boiling a litter of water (4,184 Joule/Kg*degree Celsius), with a starting temperature of 20 C, in exactly 4 minutes.

Answer 1

Answer:

The resistance is 8.7 ohm.

Explanation:

Voltage, V = 110 V

mass, m = 1 kg

change in temperature, T = 100 - 20 = 80 C

time, t = 4 min = 4 x 60 = 240 s

specific heat, c = 4184 J/kg C

let the resistance is R.

The heat generated by the heater is used to the heat the water.

$\frac{V^2}{R} t = m c T \\\\\frac{110^2}{R}\times 240 = 1\times 4184\times 80\\\\R = 8.7 ohm$