4 - Elec 2 Flashcards
Basically an electrical circuit consists of ______, ______ and _____. A) B) C) D)
-Power source -connecting wires or conductors -load or something that uses the electrical energy
The load is the device that takes electrical energy from the power source and ? A) B) C) D)
uses it to perform some useful function
All switches perform the same basic function? A) B) C) D)
Opening and closing electric circuits
The amount of voltage supplied by the source determines? A) B) C) D)
How much current will flow
2 factors that determin how much current will flow in a DC circuit A) B) C) D)
-The voltage supplied and -How well the load and wires conduct current
The ease with which a metal allows current to flow is? A) B) C) D)
conductance
_____ has the greatest conductance? A) B) C) D)
Silver
The resistance of any material depends on? A) B) C) D)
The number of free electrons the material has
By choosing the proper metal for a conductor and making it with a certain cross-section and length? A) B) C) D)
You can produce any kind of resistance effect you want
A unit of resistance is called? A) B) C) D)
Ohm
The Greek letter ______ is often used for the symbol for the Ohm A) B) C) D)
Omega
The resistance of the ______ is much greater than the resistance of the _____? A) B) C) D)
load; circuit wiring
Every power source has some? A) B) C) D)
internal resistance
Two possible methods of decreasing large current in a circuit with a fixed voltage are? A) B) C) D)
increasing the resistance of the connecting wires and adding resistors to the circuit
The materials most often used for resistors are ______, and special metal alloys, such as nichrome, constantan and manganoan. A) B) C) D)
Carbon
To account for variations resistors are marked with? A) B) C) D)
A tolerance
The wattage rating on the resistor determines? A) B) C) D)
The maximum current a resistor can carry
What are the advantages of a composition resistor? A) B) C) D)
smaller and low cost
The property of maintaining a small tolerance under all operating conditions is called the ______ of a resistor A) B) C) D)
Stability
When all 3 terminals are connected into a circuit the resistor is called A) B) C) D)
potentiometer
When only the center terminal and one other terminal are used in a circuit the resistor is called? A) B) C) D)
Rheostat
If you raise voltage ( E), ______ will go up. A) B) C) D)
Current (I)
If you lower resistance ( R), _____ will go up. A) B) C) D)
Current (I)
A good practice to always follow at this point is to think in terms of? A) B) C) D)
Knowns and Unknowns
Power is the amount of ? A) B) C) D)
Work that can be done by a load in some standard amount of time
A watt is the power used when? A) B) C) D)
One ampere of current flows through a potential difference of one volt
The power rating of working equipment is based mostly on? A) B) C) D)
The power they can use to do mechanical work
Electric companies charge their customers according to the number of? A) B) C) D)
Kilowatt hours of power they use
1000 volts = A) B) C) D)
1 kilowatt
1,000,000 volts = A) B) C) D)
1 megawatt
In a series circuit the same _____ flows through every part A) B) C) D)
Current (I)
When 2 batteries are connected in series? A) B) C) D)
The negative terminal of one is connected to the positive terminal of the other
When power sources are connected in series the total voltage is? A) B) C) D)
The sum of the individual source voltages
If power sources are connected so that their polarities are not in the same direction? A) B) C) D)
They will oppose each other
The total voltage drop equals? A) B) C) D)
the source voltage
In a series circuit there in only one current it is from? A) B) C) D)
The negative terminal to the positive terminal
When current can flow from the negative terminal of the power source through the connecting wires and back to the positive terminal of the power source without going through a load, this is called? A) B) C) D)
short circuit
_____ uses the principle of magnetism to open a circuit when too much current flows? A) B) C) D)
Electro magnetic circuit breaker
A ____ circuit is where one or more points, the current divides and flows different paths points A) B) C) D)
parallel
The total current in a parallel circuit = A) B) C) D)
the sum of the branches current
This method can be used to calculate the total resistance of any combination of parallel resistance in a circuit? A) B) C) D)
reciprocal
The total power consumed in a parallel circuit = A) B) C) D)
the sum of the power used by each individual load
Kirchhoff’s Law No 1 A) B) C) D)
The sum of the voltage drops around any closed loop equals the sum of the EMF’s in that loop
Most resistor failures result from? A) B) C) D)
the heat generated in the resistor by the current flow
EMF is measured in? A) B) C) D)
volts
The longer the wire? A) B) C) D)
the more resistance it has
What determines the resistance of a given conductor? A) B) C) D)
-cross-sectional area -length of the conductor -resistance
