Topic 2- Electricity Flashcards
Describe the energy transfers in a battery powered torch
Battery converts chemical energy into electrical energy
Bulb converts electrical energy into light as well as waste energy in the form of heating
Describe the energy transfers in a battery powered motor
Battery converts chemical energy into electrical energy
Motor converts electrical energy into kinetic energy as well as waste energy in the form of heating due to friction
What three things determine the power of a circuit device?
The potential difference across the circuit
The current through the circuit
The amount of energy transferred in a given time
What is the purpose of the National Grid?
To link power stations to consumers so that they have access to a source of electricity
What are the two types of transformers used in the National Grid?
Step-Up Transformers
Step-Down Transformers
Where are step-up transformers found in the National Grid? What do they do?
Step-up transformers are used when connecting power stations to transmission cables
They increase the potential difference
So as the power is constant, current decreases so less energy is lost
Where are step-down transformers found in the National Grid? What do they do?
Step-Down Transformers are used in connecting transmission cables to domestic buildings (like houses)
They decrease the potential difference
For consumer safety
Why do transmission lines transfer electricity at high potentials?
A high potential, results in a low current
The lower the current, the less energy that is wasted as heat
Therefore it is more efficient
Why does the potential need to be decreased between transmission lines and houses?
Lower potentials are safer for domestic use and reduces the likelihood of severe electrocution
Appliances are designed for 230V
What can happen when insulating materials are rubbed together?
They can become (statically) electrically charged
Why can insulators become electrically charged when rubbed together?
Electrons are rubbed from one material onto the other
The material gaining electrons becomes negatively charged
The material losing electrons becomes equally positively charged
What happens when two electrically charged objects are brought close together?
They exert a force on each other
What happens when two identically charged objects are brought close together?
They exert a repulsive force on each other and repel
What happens when two oppositely charged objects are brought close together?
They exert an attractive force on each other and attract
Give an example of a non-contact force
The repulsive or attractive force acting between two electrically charged objects
