Physics Flashcards
What does a.c stand for and what does it mean?
Alternating current - the current flows in different directions. On an oscillator it creates a regularly repeating wave.
What does d.c stand for and what does it mean?
Direct current - the current flows in one direction only (usually at 50V). On Oscillator it makes a straight line.
What are the three wires in a three core plug and what colours are they?
Live wire is brown.
Neutral wire is blue.
Earth wire is green with yellow stripes.
What does a fuse do?
A fuse will melt if a current surge flows through it and when it melts it breaks the circuit.
What does the earth cable do?
It is connected to the casing of metal appliances so that if the live wire touches the casing the current is taken back through the circuit and to a circuit breaker or a fuse.
Why is a circuit breaker considered to be better than a fuse?
Because it only disengages a switch which can be turned back on. It is also faster than a fuse as a fuse takes more time to break the circuit when it melts.
What is a half life?
Half life is the average time it takes for the number of nuclei in a radioactive isotope sample to halve.
What are gamma rays used for?
Sterilising food and metal instruments.
What is nuclear fission?
The splitting of large atomic nuclei which produces energy.
What happens in the process of fission?
A neutron is fired at an atom, which splits into two new atoms of different elements and three more neutrons are released which continues the process.
