Answer:
242.4 V
Explanation:
Applying,
Q = cm(t₂-t₁)................ Equation 1
Where Q = amount of heat, c = specific heat capacity, m = mass, t₁ = initial temperature, t₂ = final temperature.
But this heat is produced by electrical power
Therefore,
P = Q/t
Where P = Electrical power, t = time
Also,
P = V²/R
Where V = voltage, R = resistance
Therefore
V²/R = Q/t......................... Equation 2
Substitute equation 1 into equation 2
V²/R = cm(t₂-t₁)/t................. Equation 3
Given: R = 250 ohms, m = 4.6 kg, t₁ = 22°C, t₂ = 32°C, t = 15 min. = (15×60) = 900 seconds
Constant: c = 4600 J/kg.°C
Substitute these values into equation 2
V²/250 = 4600(4.6)(32-22)/900
V²/250 = 235.11
V² = 250×235.11
V² = 58777.78
V = √58777.78
V = 242.4 V
