Physics - Charge and Current
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What is electric current?
The rate of flow of charged paticles.
What symbol is used to represent current?
What are some examples of charged particles?
- Electrons, $e^{-}$
- Positrons, $e^{+}$
- Protons, $p$
- Ions, $Na^{+}$, $Cu^{++}$
Why is $I$ used to represent current?
Because it comes from the french “Intensity of Current”.
What are the units for current?
Amperes, $A$.
What does $1A$ mean physically?
1A is the same as 1 coulomb of charge passing a point in 1 second.
What is the formula for current?
What is electric charge?
A physical property of matter which measures how charged something is.
What are the two types of charge?
- Positive
- Negative
What happens to like charges?
They repel.
What happens to opposite charges?
They attract.
What is the symbol for charge?
Why is $Q$ used to represent charge?
Because it comes from “quantised charge”.
What are the units for charge?
Coulombs, $C$
What is the equation for charge?
What does $1C$ mean physically?
The charge that flows past a point in one second when there is a current of $1$ amp.
What is the charge of a proton, in coulombs?
What is the charge of an electron, in coulombs?
What is relative charge?
The measure of a charge as multiples of the constant $e$.
In relation to charge, what is the (non-numerical) definition of the constant $e$?
The elementary charge, the charge of a proton.
In relation to charge, what is the value of $e$?
What is the relative charge of an electron?
How can you work out the number of electrons given a charge $Q$?
Divide it by the elementary charge $e$, the charge contributed by each electron.
If an object gains electrons, what happens to its charge?
It becomes negatively charged.
If an object loses electrons, what happens to its charge?
It becomes positively charged.
What is the law of conservation of charge?
Electric charge can neither be creater nor destroyed.
What is word definition of Kirchhoff’s First Law?
At any point in an electrical circuit, the sum of the currents into that point is equal to the sum of the currents out of that point.
What is the symbol formula for Kirchhoff’s First Law?
What is $1As$ ($1 \text{amp-second}$) equivalent to?
What must be true about the currents?
What must be true about the currents?
What is the missing current?
What is the missing current?$4A$, towards the junction.
2021-01-11
What does an ammeter measure?
Amps.
What measures amps?
An ammeter.
Why is electrolysis an example of electric current?
It’s the movement of ions.
Why are fluorescent tubes an example of electric current?
It’s the movement of a combination of electrons and ions.
Why do electrons go from negative to positive?
Because they are repeled by the negative side of a cell.
Which way does conventional current flow?
From positive to negative.
Why is the direction of conventional current opposite to the flow of electrons?
Negative particles moving one way is the same as positive particles flowing another way.
When refering to current, should you refer to conventional current or the flow of electrons?
The conventional current.