Energy Flashcards
What is heat radiation?
The transfer of heat energy by infrared radiation.
How can heat energy be transferred?
By radiation, conduction or convection.
What types of energy transfer involve the transference of particles?
Conduction and convection
What is the main energy transfer in solids?
Conduction
What is the main form of heat transfer in liquids and gases?
Convection
Infrared radiation can be emitted by……
Solids, liquids and gases.
Where is infrared radiation emitted from?
The surface of an object
Describe the conduction of heat energy?
It is where vibrating particles pass on their extra kinetic energy to neighbouring particles
When does conduction work faster?
In denser solids
Describe convection:
It is when the more energetic particles move from the hotter region to the cooler region, taking their heat energy with them.
How does an immersion heater work?
See page 14 of CGP book
What are convection currents about?
Changes in density
What factors affect the rate of reaction so it will be faster?
- higher temperature
- lower density
- larger surface area
- greater airflow over the liquid
The rate of condensation will be faster if:
- temperature of gas is lower
- temperature of the surface the gas touches is lower
- density is higher
- airflow is less
How are vacuum flasks designed to limit heat transfer?
See page 16 CGP book
What is hair standing up on your skin supposed to reduce?
Heat loss by convection
How do you work out pay back time?
Initial cost / annual saving
Give the formula involving specific heat capacity
E= M x C x temp change
Energy transferred = mass x specific heat capacity x temp change
What is specific heat capacity?
The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree.
List the 9 types of energy:
Heat Sound Light Nuclear Thermal Kinetic Elastic potential Gravitational potential Chemical
How do you calculate efficiency?
Useful energy (or power) in / total energy (or power)
What is a kilowatt-hour?
The amount of electrical energy used by a 1kW appliance left on for 1 hour.
Give the 2 formulas for calculating the cost of electricity
No. Of units (kWh) = power (in kWh) x time (hrs)
AND
Cost = no. of units x price per unit
