Volts (Voltage) - Electromotive force, or potential.

Ohms - resistance

Watts - power

Amperes - Current

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Volts - Electromotive force.

Watt-hours - energy

Watts - power.

Amperes - Current.

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Think of this in terms of water; what do you call the flow of water? Current.

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This is basic electrical knowledge. Siemens are the SI Unit of electrical conductance, susceptance, and admittance. Mhos are no longer used, and were replaced as the unit of conductance by the Siemens. Coulombs are the SI unit of electrical charge, leaving Ohms, the SI Unit of resistance, denoted by the Greek symbol Omega, Ω.

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Hard to add to what is already in this question, except possibly to explain what the incorrect questions actually mean. Voltage, of course, is the electrical term for the Electromotive force that causes electron flow.

Capacitance refers to the ability to store energy in a capacitor, which will then oppose a change in voltage. Inductance refers to the ability to store energy in a coil of wire, which will then oppose a change in current. Ampere-hours is a term used to indicate the capacity of a battery -- a 50 ampere-hour battery should be able to provide 1 amp for 50 hours, or 50 amps for 1 hour.

Obviously, none of these other answers could refer to Electromotive Force.

An easy way to remember why voltage is the correct answer is by using the water analogy: think of voltage as the pressure pushing the water thru the pipe.

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Hertz is the standard unit for frequency, as used in the SI unit system. It is defined as the number of cycles per second of something periodic. For example a quartz clock ticks at \(1\)Hz. The wall outlet AC (in the US) is set to \(60\)Hz. The tone of A just below middle C is \(220\) Hz. The unit is named after Heinrich Hertz](wiki/Heinrich_Hertz). Here is a graphical example from Wikipedia.

The other (incorrect) answers here are:

• the farad - unit of capacitance
• the henry - unit of inductance
• the tesla - unit of magnetic field strength. \(31 µT\) (\(3.1 \times 10 − 5 T\)) - strength of Earth's magnetic field at 0° latitude (on the equator)

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Most metals have loosely coupled electrons in the orbit of the atoms. That makes it easier for the electrons to flow from one atom to the next. These electrons are generally thought of as a cloud in the metal structure. Because of this electron cloud, current flows quite easily in most metals.

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Most metals are good conductors; all of them conduct electricity to some extent. A conductor is something that electricity can flow through. An insulator is the opposite -- something that electricity either doesn't flow through or doesn't flow through very well.

On a ham radio test they aren't going to try to trick you by caring how good of a conductor it is, so if it's looking for a conductor look for something metallic; if it's looking for a insulator, look for something that isn't metallic. In this case, glass is the only item listed that isn't a metal, so it's the insulator.

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Alternating Current -- or AC -- is the way that commercial and residential power works where the direction of the current alternates between positive and negative at a given frequency (or hz). In the United States the most common form of AC alternates 60 times a second (60Hz) between -120V and +120V. In many other parts of the world it runs at 50Hz between -240v and +240v.

Just remember that the current alternates in direction -- 0V would be no power flow, so zero to positive or zero to negative would be alternating on and off, not alternating direction.

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Power, also known as "watts", is equal to Voltage times Current (\(P=E \times I\)). In other words, Power is the product of the electric Current multiplied by Voltage.

If you use a water flow analogy, Current (I) is like water volume Flow-rate (liters per second), Voltage (E) is like total Pressure loss along the water pipe (Newtons/square meter or Pa). Resistance (R) is inversely related to the pipe diameter - larger pipe diameter equals less resistance, like a thicker wire does. Mechanical power is then proportional to pressure loss times flow-rate ( Newton meters per second or Watts). So, Power is a RATE of Energy usage.
Power x Time = Energy ( N*m or Watt-seconds). Then, Energy is like the total water volume (liters) moved against a specified pressure loss in a specified time.

Resistance is the opposition to the current flow, so it definitely could not be considered a viable answer.

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Resistance opposes things, and currents are no exception. Any current, electrical or radio, that passes through a resistor will be met with opposition.

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Just remember, the "Frequency" determines how "frequently" the current reverses direction.

Another way to remember is to analyze the units of each term: Pulse rate (beats per second), Speed (meters per second), Wavelength (meter), Frequency (times per second, or Hz)

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