Mains electricity Flashcards
How is mains electricity produced?
It is produced by generators that produce a voltage through a process called electromagnetic induction
What happens if a magnet is moving out of a coil rather than in?
A voltage is induced in the direction opposite to if it was moved in
How does a transformer induce a voltage across a second coil round the same iron core
A changing current in one coil of a transformer will cause a changing
magnetic field in the iron core, which in turn will induce a changing potential difference
across the other transformer coil
What is the equation for calculating the voltage across each coil?
voltage across primary coil / voltage across secondary coil =
number of turns in primary coil / number of turns in secondary coil
How can the size of an induced voltage be increased?
Increasing the speed of rotation of the magnet or electromagnet,
Increasing the strength of its magnetic field,
Increasing the number of turns on the coil,
Placing an iron core inside the coil.
What is the difference between d.c. and a.c. ?
d. c. is direct current which means that the current is always in the same direction.
a. c. is alternating current which means the current alternates direction each time
What are examples of where d.c. and a.c. are most commonly used?
Direct current is the current used in batteries.
Mains electricity however is an alternating current supply.
Why is mains electricity a.c. ?
a.c. is used for mains supplies as its easier to generate than d.c. and it is also easier and simpler to distribute over long distances
