IGCSEPhysicsCambridge (CIE)Flashcards2. Thermal PhysicsThermal Properties & Temperature

Thermal Properties & Temperature (Cambridge (CIE) IGCSE Physics)

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  • FrontThermal Expansion

    Define thermal expansion.

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  • Define thermal expansion.

    Thermal expansion occurs when substances are heated due to the increased movement of the particles in the substance.

  • True or False?

    When materials are heated they contract.

    False.

    When materials are heated they expand.

  • True or False?

    In thermal expansion, the size of the particles increases.

    False.

    The particles themselves do not expand. The particles gain energy when heated, so they move around faster which causes the space between particles to increase. This leads to the overall expansion of the substance.

  • When the temperature is increased which substance expands the most?

    When the temperature is increased a gas expands the most.

  • True or False?

    In thermal expansion, solids expand more than gases. (Extended Tier Only)

    False.

    In thermal expansion, gases expand the most, then liquids, and solids expand the least.

  • Name two applications of thermal expansion.

    The two applications of thermal expansion that you need to know are:

    • thermometers

    • temperature activated switches

  • True or False?

    Railway tracks and bridges have gaps built in to accommodate thermal expansion.

    True.

    Railway tracks and bridges do have gaps built in to allow for the thermal expansion of the materials.

  • Define the term internal energy.

    Internal energy is the total energy of the particles in a system due to their motion and position.

  • True or False?

    The change in temperature of a substance that is heated depends on the mass of the substance.

    True.

    The change in temperature of a substance that is heated does depend on the mass of the substance.

  • What does the temperature increase of a system depend upon?

    The temperature increase of a system depends upon:

    • The mass of the substance heated

    • The type of material

    • The amount of thermal energy transferred to the system

  • Define the term specific heat capacity.

    The specific heat capacity of a substance is the amount of energy required to raise the temperature of 1 kg of the substance by 1 °C.

  • True or False?

    A substance with a low specific heat capacity will heat up and cool down slowly.

    False.

    A substance with a low specific heat capacity will heat up and cool down quickly. It takes less energy to create a temperature change.

  • True or False?

    Different substances have different specific heat capacities.

    True.

    Different substances have different specific heat capacities.

  • State the equation for specific heat capacity. (Extended Tier Only)

    The equation for specific heat capacity is increment E space equals space m c increment theta

    Where:

    • increment E = change in energy, measured in joules (J)

    • m = mass, measured in kilograms (kg)

    • c = specific heat capacity, measured in joules per kilogram per degree Celsius (J/kg °C)

    • increment theta = change in temperature, measured in degrees Celsius (°C)

  • What is the equation for specific heat capacity when specific heat capacity is the subject of the equation? (Extended Tier Only)

    The equation for specific heat capacity when specific heat capacity is the subject of the equation is: c space equals space fraction numerator increment E over denominator m increment theta end fraction

    Where:

    • c = specific heat capacity, measured in joules per kilogram per degree Celsius (J/kg °C)

    • m = mass, measured in kilograms (kg)

    • increment theta = change in temperature, measured in degrees Celsius (°C)

    • increment E = change in energy, measured in joules (J)

  • What are the melting and boiling points of pure water at standard atmospheric pressure?

    Pure water ice melts at 0 °C, and pure liquid water boils at 100 °C at standard atmospheric pressure. These are known as the fixed points of water.

  • True or False?

    Energy is transferred away from a substance when it solidifies.

    True.

    Energy is transferred away from a substance when it solidifies.

  • True or False?

    The temperature of a substance increases while the substance is melting.

    False.

    The temperature of a substance does not increase while the substance is melting. There is no change in temperature during a change of state. The energy is used to change the state of the substance rather than to increase its temperature.

  • True or False?

    Liquids freeze at the melting point of the substance.

    True.

    Liquids do freeze at the melting point of the substance. The state change between solids and liquids occurs at the melting point.

  • True or False?

    Gases condense at the boiling point of the substance.

    True.

    Gases do condense at the boiling point of the substance. The state change between liquids and gases occurs at the boiling point of the substance.

  • When a substance is melting or boiling, why does the temperature of the substance not change even though energy is being transferred into the system?

    The energy transferred into a substance that is melting or boiling is used to overcome the intermolecular forces of attraction holding the particles in close proximity, rather than increasing the temperature of the substance.

  • True or False?

    Freezing and melting happen at the same temperature.

    True.

    Freezing and melting do happen at the same temperature, the melting point of the substance.

  • Define the term evaporation.

    Evaporation is the change of state from a liquid to a gas. It happens at any temperature and only from the surface of the liquid.

  • True or False?

    Evaporation results in the heating of a liquid.

    False.

    Evaporation results in the cooling of a liquid.

  • How does evaporation occur?

    Evaporation occurs when more energetic particles at the surface of the liquid overcome the intermolecular forces of attraction holding them in close proximity.

  • What are the three steps in the cooling effect of evaporation?

    Evaporation cools a substance because:

    • The more energetic particles at the surface escape the liquid.

    • This reduces the average energy of the particles in the liquid.

    • Since temperature is a measure of the average kinetic energy of the particles in a substance, the temperature decreases and the substance is cooled.

  • What are the factors affecting the rate of evaporation? (Extended Tier Only)

    The factors affecting the rate of evaporation are:

    • temperature

    • surface area

    • air movement

  • What is the difference between boiling and evaporation? (Extended Tier Only)

    Boiling only happens at the boiling point of a substance, and it occurs throughout the liquid. Evaporation can occur at any temperature and it only happens at the surface of a liquid.

  • True or False?

    Objects can be cooled when a liquid evaporates from the surface of an object. (Extended Tier Only)

    True.

    Objects can be cooled when a liquid evaporates from the surface of an object. For example, when sweat evaporates from the skin:

    • Energy is transferred from the warmer skin to the cooler liquid.

    • The more energetic particles at the surface of the liquid escape reducing the average energy of the liquid.

    • This increases the temperature difference between the skin and the liquid so more energy is transferred from the skin to the liquid.

    • This process has a cooling effect on the skin.

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2. Thermal Physics
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4. Electricity & Magnetism
5. Nuclear Physics
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