Conduction is how thermal energy travels through solids.
In a solid, the particles are tightly packed together in fixed positions.
When you hold ice in your hand:
Metals are good conductors of electricity. As well as vibrations being passed from particle to particle, as described above, metals also have ‘free’ electrons that can carry energy through the solid. This means that thermal energy conducts faster through metals than other materials.
You need to be familiar with the practical method used to investigate the effectiveness of insulating materials.
Potential errors in this investigation include:
Specific Heat Capacity
The temperature change of a substance depends on the following factors:
Different substances absorb thermal energy at different rates.
The specific heat capacity of a substance is the energy needed to raise the temperature of 1kg of the substance by 1°C
∆E = mc∆θ
∆E = energy transferred (J)
m = mass (kg)
c = specific heat capacity (J/kg°C)
∆θ = temperature change (°C)
(you will be given this equation on a data sheet in the exam)
Worked Example
0.15 kg of ice cream mixture was cooled from room temperature (20°C) to 0°C. This required 6000 J of energy. What is the specific heat capacity of this ice cream?
Rearrange: c = ∆E ÷ (m∆θ)
c = 6000 ÷ (0.15x20)
c = 2000 J/kg°C
A storage heater uses electricity at night (when it is cheaper) to heat bricks or concrete blocks inside the heater.
The bricks have a high specific heat capacity so they warm up slowly and then cool down slowly during the day, releasing thermal energy into the room. This is cheaper than using hot water in radiators but offers less control over the temperature of the room.
You need to be familiar with the practical procedure used to find the specific heat capacity of a given material.
The value you calculate for specific heat capacity is unlikely to be exactly the same as the published values for the same material.
This is due to errors in the investigation, including:
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