Resistance/ Conductance/ Ohm's Law

Milliamperes can be converted to amperes by

moving the decimal point three places to the left So 500 mA would be the same as 0.5 A

Millivolts

1/1,000 of a volt

The relationship that exists between resistance and conductance is

A reciprocal one

Small voltages

Be expressed as millivolts (mV)

The strength or intensity of the current is

Directly proportional to the voltage and inversely proportional to the resistance.

The unit of conductance is the

Simeon ( formerly the mho which is ohm spelled backwards)

Voltage can be given in a number of different units

Small voltages & Large voltages

Resistance varies inversely with the Size if the conductor in cross section in other words ?

The larger the wire , the smaller the resistance per foot of length (increases and decreases)

Ohm's Law

The relationship between voltage, current, and resistance

If the resistance of a material is known , dividing its value into 1 will

give its conductance

A reciprocal of a number

is one divided by that number

Conductance

is the ability of a material to pass electrons.

One ohm is -

is the amount of resistance that will allow one ampere of current to flow if one volt of electrical pressured is placed on a conductor.

Resistance is often expressed as

kiloohms (KΩ) or megaohms (MΩ)

Large voltages can be expressed as

kilovolts ( KV) or even megAvolts ( mV)

Resistance varies directly with the

length of wire

The formula E = I x R is used to find ?

To find the emf( voltage) when the current and the resistance is known

Thermistors decrease in resistance with an increase in

With an increase in Temperature

Thermistors

change resistance with temperature.

The factors that affect the magnitude of resistance are exactly the same for

conductance, but they affect conductance In the opposite matter

Ohms law states that voltage in volts is ?

equal to the current in amperes multiplied by the resistance in ohms This is represented by the formula E= I x R

The symbol use the represent conductance is

(S)

A KΩ (kiloohms) is

1,000 ohms

A KV is

1,000 volts

A MΩ (megaohms) is

1,000,000 ohms

mV is

1,000,000 volts

Resistance in a conductor depends on four factors

1. Material 2. Length 3. Crossectional area 4. Temperature

Milliamperes

3 places to the left

Kiloohms KΩ

3 places to the right

Converting to volts requires the decimal point to be move

6 place to the right 6 mV is than becomes 6,000,000 V

Megaohms can be converted to ohms by moving the decimal point

6 places To the right. 10MΩ would be the same as 10,000,000 Ω

Megaohms MΩ

6 places to the right

All conductors have ?

A certain amount of resistance , with some having more than others

Ohms law is very useful in

Electrical and electronics work, you will need it often to determine the missing value

The formula for conductance is

G= A/pL G= conductance measured in Siemens (s) A= cross-sectional area in cir mils L= length measured in feet P= specific resistance

Georg Ohm

German physicist who found in 1827 that in any circuit where the only opposition to the flow of electrons is resistance , there is a relationship between the values of voltage , current, resistance.

Resistance makes it possible to generate ?

Heat , control electron flow, and supply the correct voltage to a device.

To find the current when the voltage and resistance are known use

I = E/R

Resistance can be measured using an ?

Ohmmeter

When using ohms law the quantities must be expressed in ?

Ohms , amperes ,and volts If any of these quantities are given on other units these should be converted before making calculations with them

In terms of resistance and conductance

R= 1/G (conductance measured in Siemens (S) G=1/R

To find the resistance when the voltage and current is known

R=E/I

For most materials , the higher the temperature ,

The higher the resistance

Thermistors are used in certain types of meters to measure ?

Temperature

Milliamperes (mA)-

is 1/1,000 of an ampere

Current is often expressed in

milliamperes

Resistance is measure in ?

ohms

Resistance -

opposition to the flow of current

I

represents current. Current is the rate of flow of electrons , or intensity of the flow. I is the rate of charge of flow

R

represents resistance

E

represents voltage. this is best remembered as electromotive force (emf) which is another word for voltage.

Conductance is the opposite of

resistance

If the conductance is known, dividing its value into 1 will give its

resistance.

Conductance is directly proportional to area and inversely proportional to

the length and specific resistance of the material

The longer the wire or conductor

the more resistance it's has

Some materials offer more resistance than others , depending On ?

the number of free electrons present I'm the material

Converting mV to V requires that the decimal point be moved

three places to the left 1,000 mV would be the same as 1V

converting KV to V requires the decimal place to be moved

three places to the right 3KV is the same as 3,000 V

To convert kiloohms into ohms , move the decimal point

three places to the right. 6 KΩ would them become 6,000 Ω

The symbol for ohm is

Ω (omega)