An electric stove with a resistance of 40 ohms is connected to a network with a voltage of 220 volts

| February 13, 2021 | education

An electric stove with a resistance of 40 ohms is connected to a network with a voltage of 220 volts. After what period of time the water in a saucepan will boil on this stove with a temperature of 20 degrees and a volume of 2 liters.

Q1 = Q2.

Q1 = U ^ 2 * t / R, where U is the voltage (U = 220 V), t is the operating time of the tile, R is the resistance (R = 40 Ohm).

Q2 = C * m * (tк – tн), where C – beats. heat capacity of water (C1 = 4200 J / (K * kg)), m is the mass of heated water (m = ρ * V, where ρ is the density (ρ = 1000 kg / m3), V is the volume (V = 2 l = 2 dm3 = 2 * 10 ^ -3 m3)), tк = 100 ºС, tн = 20 ºС.

U ^ 2 * t / R = C * ρ * V * Δt.

t = C * ρ * V * (tk – tn) * R / U ^ 2 = 4200 * 1000 * 2 * 10 ^ -3 * (100 – 20) * 40/2202 ≈ 555 s = 9 min 15 s.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.