Question

Электрический кипятильник кпд которого 75%, за 3 минуты передал воду количество теплоты 41 кДж. Каково напряжение на кипятильнике? если его сопротивление 12 Ом?

Answer 1

Дано:n=80%=0,8s=0,84мм^2p=1,1с=4200Дж/кг*CU=220BT=20мин=1200cm(воды)=4кгt1=10t2=20дельтаt=10Найти l?Решение:n=mc*дельтаt/UII=U/RR=pl/sn=mc*дельтаt/U^2S/plnU^2S=mc(t2-t1)pll=nU^2S/mc(t2-t1)pl=0,8*48400*0,84/4*4200*10*1,1=32524,8/184800=0,176мОвтет:0,176м

Answer 2

Calculation of Voltage on the Electric Kettle

To calculate the voltage on the electric kettle, we can use the formula:

Power (P) = Voltage (V) x Current (I)

We are given the following information: - Efficiency (η) = 75% = 0.75 - Time (t) = 3 minutes = 180 seconds - Heat transferred (Q) = 41 kJ = 41,000 J - Resistance (R) = 12 Ω

First, let's calculate the power (P) using the formula:

Power (P) = Heat transferred (Q) / Time (t)

Substituting the given values:

P = 41,000 J / 180 s = 227.78 W

Since the efficiency (η) is given as 75%, we can calculate the actual power consumed by the kettle using the formula:

Actual Power (P_actual) = Efficiency (η) x Power (P)

Substituting the values:

P_actual = 0.75 x 227.78 W = 170.84 W

Now, we can calculate the current (I) using the formula:

Power (P_actual) = Voltage (V) x Current (I)

Rearranging the formula:

Current (I) = Power (P_actual) / Voltage (V)

Substituting the values:

I = 170.84 W / Voltage (V)

Finally, we can calculate the voltage (V) using Ohm's Law:

Voltage (V) = Current (I) x Resistance (R)

Substituting the values:

Voltage (V) = (170.84 W / Voltage (V)) x 12 Ω

Simplifying the equation:

V^2 = 170.84 W x 12 Ω

V^2 = 2050.08 WΩ

Taking the square root of both sides:

V = √(2050.08 WΩ)

Calculating the value:

V ≈ 45.29 V

Therefore, the voltage on the electric kettle is approximately 45.29 V.