Electricity basics Flashcards
What is a conductor?
A material that allows charge to flow through it.
What is an insulator?
A material that does not allow charge to flow through it.
Why does rubbing a glass rod with a silk cloth cause the rod to gain a positive charge?
Rubbing the glass rod with the silk cloth causes electrons to be transferred from the glass rod to the silk cloth, which means the glass rod has an overall positive charge.
What is current, what are its units, how is it measured?
Current is the rate of flow of charge, (Charge/Time) it has the units Ampere/Amps (A) and can be measured with an ammeter.
What is the charge of an electron?
Negative (-1.60 x10^-19)
How are metal atoms bonded together?
Atoms lose one or more elctrons, which become delcocalised electrons. Metals are postivie ions held together by a sea of delocalised electrons.
Are metals good conductors or insulators? Why?
Metals are good conductors as they have free electrons that can move to carry a charge.
Why are metals good at transferring heat?
Delocalised electrons collide with eachother and lattice ions which causes energy transfer, therefore the free movement and collisions mean metals have high thermal conductivity.
What is the definiton of potential difference?
The P.D between two points is the energy converted from electircal potential energy to some other form per unit charge.
What is Ohms law?
The current through a conductor is proportional to the potential difference, when the temperature is constant - (An ohmic conductor is a device whihc obeys Ohms law)
What is resistance?
Resistance of a conductor is the potential difference across the conductor, divided by the current.
Describe and explain the shape of a current, voltage graph for a lamp filament.
At low potential differences, the graph is a straight line as the bulb is obeying Ohms law. At high potential differences, the bulb begins to heat up whihc increases the resistance so gradient of line decreases.
