Flashcards
Science
Flashcards do conjunto (26)
- 1What the difference between c open and closed electrical circuits?Circuits is path which electricity flow. Open is one path that is incomplete or interrupted and electricity will not flow. Closed is the path of which electricity is applied and flow once the circuit is closed with a complete path.
- 2How do currents work?The flow of electrons around a electrical circuit, from the electricity source to a point of load.
- 3How is the strength of currents measured?In amperes (A) and represented by the symbol I (intensity)
- 4What are 2 forms of electrical currents?Direct current (DC)
Alternating current (AC) - 5Describe direct current.The flow of electrons in one direction, from the negative to the positive terminal of the power source (typically a battery). The higher the voltage (V) of the power source, the more electrons are available to the circuit and the greater the load that can be powered.
- 6Describe alternating currents.The flow of electrons periodically reverses direction. Voltage and current in an (AC) circuit take the form of a sine wave and is rated by the number of cycles per second (frequency) of this wave in hertz (Hz).
- 7What is resistance? How is it measured?All materials have a certain amount of resistance to the flow of electricity. The more resistive the material, the slower the flow of electricity will be. Resistance is measured ohms ( Ω ) and equal to the voltage across the material divided by the current present in it ( V/I ).
- 8What is a conductor?is a material through which electrical current can flow with little resistance.
- 9What is a insulator?is a material that resists electrical current
- 10What is a semiconductor?is a material that has conductivity partway between a conductor and an insulator with the primary advantage of showing increased conductivity with increased temperature unlike conductors where conductivity decreases with increased temperature.
- 11Explain OHM'S LAWA set relationship exists between voltage (V), resistance (R), and current (I) in an electrical circuit:
Current is voltage ÷ resistance:
I = V / R
Resistance voltage ÷ current:
R = V / I
Voltage is resistance x current:
V = I x R - 12How is power measured?Power represents the overall amount of electricity that a device needs to operate and is measured in watts (w). One watt equals one ampere multiplied by one volt or
P = V x I. - 13What is the most common type of direct current (DC) people use?Batteries
- 14What are differences between dry cell and wet cell batteries?Dry cell batteries are AA, C, D.
Wet cell batteries are used in cares, and storages like backup and emergency batteries. - 15______+ ___ Signs on batteries. What do these mean?______+
This is call the long bar of the battery schematic is positive terminal.
___
This is the short bar is the negative
terminal. - 16Why are batteries connected in series?To provide voltage equal to the sum of their individual voltages with a current equal to the current that a single battery produces.
- 17Why are batteries connected in a parallel current?to provide current equal to the sum of their individual currents with a voltage equal to the voltage that a single battery produces.
- 18To increase both voltage and current what would you do?Connect batteries in a
series-parallel configuration formation. - 19What does Photovoltaic or solar cell batteries do?convert energy from the sun into electrical energy. They are made of semiconductors, and often charge other types of batteries.
- 20What is electrical wiring used for?used to connect circuits and equipment and different electrical applications require different types and sizes of wire.
- 21When choosing the correct electrical wire size what principal factor do you need to keep in mind?The amount of current that will be traveling through the wire – the higher the current, the larger gauge wire required to prevent the wire from overheating.
- 22What is it called when electrical wire need to be spliced or connected?Most commonly done by soldering where a tin-lead mixture is applied to the wire ends and allowed to cool, producing a connection that maintains the conductivity and strength of the original wires.
- 23What is a coaxial cable?Type of electrical wiring it is used to transmit radio frequency. Constructed with a flexible insulating layer surrounding fine woven wire, coax is used in computer networks, antenna connections, and cable/satellite wiring.
- 24A resistor is designed to do what?Limits the amount of current flowing through a circuit and is used to precisely control the amount of voltage and current present at various points within an electrical circuit. When current flows through a resistor the resistor produces heat and managing heat within the circuit is a very important design consideration for engineers.
- 25Explain how a capacitor works.Stores an electric charge using two parallel plates with a a nonconducting material (dielectric) between them. Capacitors can provide a fixed or variable capacitance in a circuit. Capacitance is measured in farads (F) and depends on the surface area of the plates (larger means higher capacitance), their distance apart (closer means higher capacitance), and the type of dielectric.
- 26How does a switch work on a device?For opening and closing an electric circuit – when open, no current flows. Switches are categorized by the number of poles and throws they provide with the number of poles designating the number of electrical circuits the switch can control and the number of throws indicating the number of connections the switch can make between those circuits.