Physics (Electrical Charges) Flashcards
What is the difference between positive charges an negative charges?
Positive charges are the charges of protons. Protons are part of the nucleus of atoms and are held firmly in place. They cannot be rubbed off when materials are rubbed together.
Negative charges are the charges of electrons. Electrons can be rubbed off, because they surround the nucleus and some are not tightly bound to it.
What happens to to the electrical charge of two materials both before and after they are rubbed together?
Before two materials are rubbed together, they have equal numbers of positively charged protions and negatively charged electorns. They cancel each other out so the materials are electrically neutral.
When two materials are rubbed together, electrons can be transferred. If electrons are rubbed off of one material, the protons stay behind and the material becomes electrically charged. So does the material that gains the electrons. A material that is electrically charged has an unequal number of positive and negative charges.
What is the Law of Electric Charge?
The Law of Electric Charge states that opposite charges attract each other and like charges repel each other.
The law of electric charge also explains why charged objects attract neutral objects.
For example, a charged balloon will stick to an electrically neutral wall.
How does a battery work?
A battery is an electromechanical cell. In a cell, chemical reactions of two different metals or metal compounds occur on the surface of electrodes. The electrodes are in a solution called an electrolyte. The reactions cause one electrode to become positively charged and the other to become negatively charged. The electrodes are in contact with terminals in the cell. When terminals are connected to an electrical pathway, charges flow through it.
What are the two types of cells for batteries?
Dry cell: Such as a AA battery, contains a moist paste as an electrolyte.
Wet cell: The electrodes sit in a liquid solution. A car battery is an example of a wet cell.
How does a Cell work?
In a cell, chemical reactions separate positive and negative charges. Because work goes into separating the charges, the electrons now have the energy to do other work, like running a laptop. The energy stored in the cell is electrical potential energy.
What is Electrical Potential Difference?
When a unit of charge passes through a source, such as a cell or battery, it gains electrical potential energy. The quantity used to measure this is called electrical potential difference. It is determined by the nature of the chemical reaction that takes place in the cell. When cells are connected in a battery, their electrical potential differences add up.
What is Conductivity and Current?
A conductor is a type of material that allows electrical charges to flow through it.
Moving charges are called an electric current.
What is an insulator?
A material through which electrical charges cannot travel at all.
What is conductivity?
How easily the charges move through a material.
What is a load?
A device that converts electrical energy into another form of energy. Light bulbs and radios are examples of loads.
What is resistance?
The degree to which the flow of current is hindered.
What is an electrical circuit?
An electrical circuit forms when a source, load and conductor are connected in a way that allows current to flow. For the current to flow, a circuit must be closed (form a closed loop).
What is a short circuit?
In a short circuit, the current can get very high because there is no load. The conductor can get hot enough to start a fire.
What is an open circuit?
If there is no closed path along which current can flow, the circuit is called an open circuit.
What are the key smbols used to communicate what is happening in a circuit?
V: Volts. Electrical Potential Difference.
I: Current. It is measured in amperes (A)
R: Resistance. It is measured in ohms (Ω)
Circuits are also drawn using symbols.
