3.3 Flashcards
What is a potential difference?
Two differently charged points
What is a coulomb (C)?
6.24 x 10 ^ 18 electrons
+
C = 1As (1 ampere-second)
What is the formula for Voltage?
V = IR
What is the formula for charge?
Q = I(current) x t (time)
What is the symbol for charge?
Q
Mobile positive charges are found in…?
Liquids and Gases
The direction of electrons flowing in a conductor depends on what?
The polarity of the applied voltage
What is electrolysis?
The decomposition of chemical compounds by passing an electric current through a liquid
A DC current will decompose water into Hydrogen and Oxygen. Which poles will you find each of these?
Negative: Hydrogen
Positive: Oxygen
The application of gases can be found in filament bulbs with a higher electrical output of what?
> 60W
What gases do high-capacity lamps use?
Halogens = Iodine or Bromine
What is the electron beam tube/Braun tube also known as?
The electron gun
Which one is the positive and which one is negative when referring to a cathode and anode?
Cathode: Negative
Anode: Positive
What is direct current?
When the direction and charge flowing is constant
What is the EMF?
Electromotive force (voltage)
If the current remains constant in a conductor, what remains the same?
The amount of electrons flowing per second regardless of its cross-sectional area
A current which periodically changes its flow direction is called what?
Alternating Current (A/C)
What is not a conductor in its pure form?
Water
In order to protect the filament from burning in light bulbs, what gases can be used?
Nitrogen, argon or krypton
What is an example of using electron current in a vacuum?
Oscilloscopes and Oscillographs
What is the definition of direct current?
When the direction and the amount of charge flowing is constant.
What is a closed circuit?
A complete circuit with no breaks
What is an open circuit?
A circuit that is broken and not complete
What is a CRT?
Cathode Ray Tube
Why is the electron beam oscilloscope mainly used today?
Because it’s versatile, easy to operate and shock-resistant
If not specified, which way does current always flow?
From positive to negative (conventional current)
When does an electrical voltage occur?
When there is a deficiency of electrons at one point and an excess of electrons in another point.
How can you generate a voltage?
By separating positive and negative charges
What is electrical charge?
The sum of billions of electrons and charges involved in every electrical process. The quantity of electricity.
In metals, only negative charges move. Which way would the electron flow occur?
In metals, electrons always move in the opposite to the conventional current flow. They would flow from negative to positive
What is conventional current flow?
The direction of movement of positive charges. (Positive to negative)
Which gases are used inside fluorescent tubes?
Neon and helium
Oscillographs provide what?
Rapidly varying processes which can be permanently recorded.
Oscilloscopes provide what?
Rapidly varying electrical processes which can be visualised but not recorded.
What is the electron beam tube also known as?
Braun tube
How does a Braun tube work?
An evacuated glass bulb with a cathode on one side and an anode on the opposite side. Cathode is heated, electrons released and emitted. Attracted to and accelerate towards the anode.
What happens inside fluorescent tubes?
Heat causes the molecules of the helium or neon to move in random layers. Electrons of few atoms are split up by external energy supply. Freely moving ions are generated.
What is electrical current?
A flow or movement of electrons in one direction caused by a voltage, and will follow conventional current flow. It will flow in a closed path.
What is voltage?
The difference between two electrically charged points. Having a potential difference. Also know as EMF. Exerts a force on electrons causing them to move.
