[Science 1] Electricity Flashcards
What is the Electrostatic/Coulomb force?
The force of repulsion or attraction between two like and unlike charges
Why does most matter act as if there is no electric charge at all?
Because ordinary matter has zero net charge (excess charge)
In what conditions does static electricity form?
Disruption of the balance between protons and electrons
What is charge?
Amount of electrons
What is the unit of charge?
Coulomb (C)
What is an object that can easily gain or lose electrons?
Conductor
Why are metals good conductors?
Free electrons (allows electrons to move freely through the material)
What is a net negative charge?
More electrons than protons - - & vice versa
What is an object that does not easily gain or lose electrons?
Insulator (ex. glass, plastic)
What does “being polarised” mean and for what types of things does this phenomena occur?
-Occurs in insulators
-Instead of gaining or losing electrons, the charges within the insulator shift slightly. This causes one side to become more positive and the other side more negative without changing the overall charge.
What is the purpose of an electroscope? What kind of environment are they in?
-Detect the presence of an electric charge on a body
-Isolated from the environment to prevent charge loss
What can we use to determine if something is positively or negatively charged (by relative position of the item)?
Electrification series
What happens if a positive rod moves closer to the electroscope?
The electrons on the metal disk would move towards the rod(Protons on the metal desk would still stay where they are due to the strong nuclear force). And since the protons originally on the leaves does not have electrons to cancel them out, the protons repulse, and the leaves becomes positive, moving it further apart. If this happens, it’ll mean that it’s a positively charged electroscope.
What happens if a negative rod moves closer to the electroscope?
The electrons on the metal disk would go down towards the leaves. However, since there are still protons left in the leaves (since protons remain fixed because of the strong nuclear force), the electrons and protons would cancel out and the leaves move closer together.
How are electrical shocks from static electricity caused?
Electrons jumping from one charged object to another due to an imbalance of electrons
What is voltage?
Pressure that pushes electricity to flow in a certain direction (aka electro-motive force)
What is the flow of electrons called?
Electric Current
What is electric discharge
Quick release of built-up electric charge from an object, causing the side where there are excess electrons (negative charge) to move towards the side where there is a lack of electrons (positive charge)
What was the idea in the conventional current?
An original assumption that people had, where they thought that electric currents flowed from + to -, before electrons were discovered
What is resistance?
Force that electrons experience when bumping into particles in; for example, air (More resistance —> less current flow; electrons slow down)
What is the unit of resistance?
Ohm (Ω)
What is the unit of current?
Ampere (A)
Is current (I) proportional or inversely proportional to voltage (V)?
Proportional
What is the difference between lightning and static electricity?
Lightning has more amount of static electricity to create a larger (& destructive) burst
Is current (I) proportional or inversely proportional to resistance (R)?
Inversely proportional
How do you create an electricity flow between two neutral conductors?
Create a negative charge on one conductor so that it creates an induced charge on the other conductor and increase its charge so that it can create a burst of electricity flow as you move the two conductors closer together.
What is a circuit?
A complete path that electricity flows through
What is a short circuit and why is it dangerous?
-Electricity flowing through a path with little to no resistance
-Causes too much current to flow quickly —> Increase heat & could lead to fire
What do we need to create a complete useful circuit?
A power source, A conductor (moves current because they have free electrons), An electric component (blocks that control current; a load)
What is an open circuit?
-A break in the circuit —> No current flows
-The opposite of this is a closed-circuit
What are the two ways to connect components in a circuit?
Series and Parallel
What is a series circuit?
A type of electrical circuit where all the blocks are connecting in one loop
What is a parallel circuit?
A type of electrical circuit where each component has its own direct path to the power source, forming multiple loops.
What is the benefit of a parallel circuit?
In a parallel circuit, each component has its own separate path to the power source so if you disconnect or “open” one path, it won’t stop the current in the other paths.
What is a wiring diagram?
A diagram that shows the actual components, positions, and arrangement of a circuit (in a precise drawing)
What do we use to replace wiring diagrams? (since its complicated)
Circuit diagrams
What does a circuit diagram use?
Electrical schematic symbols
How should you connect an ammeter in?
Series
What is the purpose of an ammeter?
Measures current
If you don’t know the exact voltage, what current should you pick, and why? (50mA, 500mA, 5A)
5A (Because its less sensitive)
What is the purpose of a voltmeter?
Measures the voltage between two points in a circuit
How should you connect the voltmeter?
Parallel
Is the current the same or different at every point in a series circuit?
Same (because there is only one path that electricity can follow, and it is the flow of electrons)
The __________ is equal to the current flowing in and out in a parallel circuit. Fill in the blank.
The sum of the currents through each path
What is a DC power supply?
Battery (direct current; electricity only flows in one direction)
The ________ is equal to the voltage of the power supply in a series circuit. Fill in the blank.
Total sum of “voltage drops” (voltage lost by components)
_________ is equal to the voltage of the power supply in a parallel circuit.
Each part of the path
What is the purpose of circuit breakers?
To prevent too much current from flowing into the house
What is the purpose of resistors in an electric circuit?
Creates a blockage to make it difficult for electricity to flow
What is a point where two or more wires connect in a circuit called?
Junction (Node)
What does the Junction Rule (Kirchhoff’s First Law) state?
The sum of the currents flowing into a junction = the sum of the currents flowing out.
What does Kirchhoff’s Second Law (Voltage Law) state?
The sum of voltage drop around any closed loop is zero
Why are insulators hard to pass an electric current to?
Resistance is too strong
What are the three things that affect a wire’s resistance?
Type of metal, length, thickness (cross-sectional area)
What is resistance proportional to in a wire?
Length
What is resistance inversely proportional to in a wire?
Area (thickness)
