An immersion heater is rated 120W. How long does it take the heater to raise the temperature of 1.2kg of water by 15oC. (Assuming heat lost to the surroundi...
Question 1 Report
An immersion heater is rated 120W. How long does it take the heater to raise the temperature of 1.2kg of water by 15oC. (Assuming heat lost to the surrounding is negligible. Specific heat capacity of water = 4200 Jkg-1K-1C)
Answer Details
We can use the formula:
Q = mcΔT
where Q is the amount of heat required to raise the temperature of the water, m is the mass of water, c is the specific heat capacity of water, and ΔT is the change in temperature.
First, let's calculate Q:
Q = (1.2 kg) x (4200 Jkg^-1K^-1) x (15°C) = 75600 J
This means we need to supply the water with 75600 J of heat in order to raise its temperature by 15°C.
Now, let's use the formula:
P = Q/t
where P is the power of the immersion heater (in watts), t is the time taken (in seconds), and Q is the amount of heat supplied to the water.
Converting 120W to J/s, we have:
P = 120W = 120 J/s
Plugging in the values for P and Q, we get:
120 J/s = 75600 J/t
Solving for t, we get:
t = 75600 J / 120 J/s = 630 s
Converting to minutes, we get:
t = 630 s / 60 s/min = 10.5 min
Therefore, it would take 10.5 minutes for the immersion heater to raise the temperature of 1.2 kg of water by 15°C.
Answer: 10.5 minutes
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