# 2 spirals of an electric stove with a resistance of 10 ohms each are connected in series and connected

**2 spirals of an electric stove with a resistance of 10 ohms each are connected in series and connected to a 220 V network. After what time will water boil on this stove weighing 1 kg, poured into an aluminum pan weighing 300 g, if their initial temperature is 20 degrees. Neglect energy losses for heating the environment (specific heat capacity of water is 4200 joules per kilogram, specific heat capacity of aluminum is 920 joules per kilogram, boiling point of water is 100 degrees.**

1) Since the spirals of the electric stove are connected in series, their total resistance is equal to the sum of the resistances of each of them, that is, R = 10 Ohm + 10 Ohm = 20 Ohm, the power of the tile will be

N = (U • U): R = 2420 W.

2) Water and a saucepan for heating from an initial temperature of 20 degrees to a boiling point of water of 100 degrees will absorb energy Q = Qw + Qk, where the general formula for calculating the amount of heat consumed: Q = m • c • Δt; temperature change Δt = (t2 – t1) = 80 (degrees); for water Qw = 1 • 4200 • 20 = 84000 (J);

for a pan Qk = 0.3 • 920 • 20 = 5520 (J); total Q = 89520 (J).

3) If the losses are neglected, then the energy released by the electric stove was spent on heating the pan with water: Q = N • τ, the process before boiling took place during the time τ = Q: N = 89520: 2420 = 36.99 s.

Answer: the water will boil in 36.99 seconds.