Energy Flashcards
What factors affect the energy transfer when charge flows through a component
Amount of charge
The potential difference across the component
Equation linking energy, current and p.d
Energy=P.D x current x time
Define potential difference in terms of charge
The work done per unit of charge
Equation relating potential difference to charge
Energy transferred=charge x p.d
When an electrical current flows through a resistor why does it heat up
There are collisions between the electrons and ions in the resistor’s lattice. This causes a transfer of kinetic energy into thermal energy, which is released into the surrounding
How do low resistance wires reduce unwanted energy transfers
A smaller resistance will mean there are fewer collisions, therefore less energy will be wasted through heated
What are some advantages of the heating effect
It is useful for appliances such as toasters or electrical fires, where the heat is the desired product
What are some advantages and disadvantages of the heating effect
The loss of energy as heat energy can make an appliance inefficient
If an appliance overheats it can catch fire or overheat, which could ruin the device or injure the user
Energy transferred per second is also known as
Power
Define power
The rate of energy transfer , or the rate at which work is done
What units of power
Watts, W
Equation linking power and potential difference
Power = current x p.d
An equation linking power without p.d
Power = current^2 x resistance
Give an equation linking power and energy
Power = energy/time
Give equations linking power and resistance
Power = current ^2 x resistance
Power = p.d ^2 / resistance
