Energy Equations Flashcards
What is the equation for efficiency?
Useful power output/ total power input
What is the equation for kinetic energy?
1/2mv squared
What is the equation for gravitational potential?
Ep= mgh
What is the equation for elastic potential?
Ee= 1/2 ke squared (1/2* spring constant* extension squared)
What is the equation for specific heat capacity?
Mass* specific heat capacity* temp change
What is the specific latent heat of vaporisation?
The energy needed to change the STATE of a 1kg of substance from liquid to gas or gas to liquid
What is the equation for work done?
Force* distance
What are the 8 energy stores?
- chemical
- kinetic
- gravitational
- elastic
- thermal
- magnetic
- electrical
- nuclear
What are the 5 energy pathways?
-Mechanically
- electrically
- heating
- radiation
How do thermal power stations work?
Coal burnt to produce electricity+ small bit of chemical energy converted to useful electrical energy. Waste energy lost into surroundings
What is the difference between metal and plastic?
Plastic= insulator
Metal= conductor
What is the difference between alternating current and direct current?
Current in direct current only flows in one direction
Alternating current flows in different directions and can change in magnitude
What happens to wastes energy?
Converted to thermal+ transferred to the surroundings
What is the national grid?
A system of cables and transformers connecting power stations to homes and businesses
Electrical appliances are connected using the three core cable, what are the three cables?
- brown (live wire)
- blue (neutral)
- yellow/green ( earth wire)
What is the pd of the brown wire?
230V
How do we recognise a fault in the appliance by the earth wire?
If it’s not 0V
What is the fuses job?
Melts/ stops flows of circuit if there is an excessive current
What does a diode do?
allows current to flow one way in a circuit
What does a resistor do?
Provides fix resistance
What is a variable resistor?
Component whose resistance can be changed
What does a thermistor do?
Changes resistance with temperature. (Higher temp= lower resistance)
What does an LED do?
allows current to flow only one way
What does an LDR do?
Has resistance that changes
What is the current like in a series circuit
Same in all points
What is the PD like in a series circuit?
Shared between components equally if identical resistance
What is the current like in a parallel circuit?
Current shared among branches
What is the PD like in a parallel circuit?
Same across all components
What is the resistance like in a parallel circuit?
Less than that of the lowest resistor
