Title: Module 3: Units
Course: Basic Electrical Theory and Wiring (Sandbox) > Section: Module 3: Voltage

Introduction

Units help us define what we are talking about. For instance, if I just said that the outlet had a lot of voltage, it doesn't mean much. However, if I say that the outlet has 120 V, then most people understand what that means. This understanding comes from the units. However, units can be difficult.

The following video will teach you about units and about how to discuss these units.

What is milliamp? What is Megaohms? We will discuss what these mean and how to address the most common units that you will see in basic electrical. Select a prefix from the drop down below to see each value.

Prefix (symbol) | Value
milli (m) | 1/1000
micro (µ) | 1/1000,000
nano (n) | 1/1000,000,000
Pico (p) | 1/1000,000,000,000
kilo (k) | 1000
Mega (M) | 1000,000
Giga (G) | 1000,000,000
Tera (T) | 1000,000,000,000

Using the prefixes, I can change my units so that it makes more sense. The following is an example for common units that we will use.

Electricity

Volts (v) Examples

Let's say that I have 1000 volts. This would be displayed as 1000 V. We know from the table above that kilo means 1000. So, 1000 V = 1 kV or 1 kilovolt. Calculate your value. Then mouse over the black box to see if you are correct.

 | Formulas |
kV * 1000 = V

V / 1000 = kV

 | Examples |
2500 V = 2.5 kV

17 kV = 17000V

120 V = 0.120 kV

480 V = 0.480 kV

Millivolts (mV) Examples

From the chart, we see that a millivolt is 1/1000 of a volt. This means that for every volt, I have 1000 mV. So, if I have 2 V, I have 2000 mV. Below are some examples. Calculate your value, and then mouse over the black box to see if you are correct.

 | Formulas |
mV / 1000 = V

V * 1000 = mV

 | Examples |
2500 mV = 2.5 V

500 mV = 0.5 V

50 V = 50,000 mV

350 mV = 0.35 V

Current

Amps (A) Examples

Let's say that I have 1000 Amps. This would be displayed as 1000 A. We know from the table above that kilo means 1000. So, 1000 A = 1 kA or 1 kiloamp. Below are more examples. Calculate your value, and then mouse over the black box to see if you are correct.

 | Formulas |
A / 1000 = kA

kA * 1000 = A

 | Examples |
1500 kA = 1,500,000 A

1500 A = 1.5 kA

17.3 kA = 17,300 A

Milliamps (mA) Examples

Let's talk about milliamps or mA. From the chart, we see that a milliamp is 1/1000 of an amp. This means that for every amp, I have 1000 mA. So, if I have 2 A, I have 2000 mA. Calculate your value, and then mouse over the black box to see if you are correct.

 | Formulas |
A * 1000 = mA

mA / 1000 = A

 | Examples |
1 A = 1000 mA

20 mA = 0.020 A

4 mA = 0.004 A

50 A = 50,000 m

50 mA = 0.050 A

100 mA = 0.10 A

Resistance Examples

Ohm (Ω) Examples

Let's say that I have 1000 ohms. This would be displayed as 1000 Ω. We know from the table above that kilo means 1000.  So, 1000 Ω = 1 kΩ or 1 kiloohm. Below is more kΩ examples. Calculate your value, and then mouse over the black box to see if you are correct.

 | Formulas |
Ω / 1000 = kΩ

kΩ * 1000 = Ω

 | Examples |
2 kΩ = 2000 Ω

500 Ω = 0.5 kΩ

50 kΩ = 50,000 Ω

Megaohm (MΩ) Examples

From the chart, we see that a megaohm is 1,000,000 x 1 Ω. This means that for every 1 MΩ, I have 1,000,000 Ω. So, if I have 2 MΩ, I have 2,000,000 Ω. Below are some examples of MΩ. Calculate your value, and then mouse over the black box to see if you are correct.

 | Formulas |
Ω * 1,000,000 = MΩ

kΩ * 1000 = MΩ

MΩ/ 1,000,000 = Ω

MΩ/1000 = kΩ

 | Examples |
1.5 MΩ = 1,500 kΩ = 1,500,000 Ω

0.5 MΩ = 500 kΩ = 500,000 Ω

0.75 MΩ = 750 kΩ = 750,000 Ω

Power

Watt (W) Examples

Common units for power are watts (W), kilowatts (kW), and megawatts (MW).

Let's say that I have 1000 Watts. This would be displayed as 1000 W. We know from the table above that kilo means 1000. So, 1000 W = 1 kW or 1 kilowatt. Below are more examples. Calculate your value. and then mouse over the black box to see if you are correct.

 | Formulas |
W / 1000 = kW

kW * 1000 =W

 | Examples |
15 kW = 15,000 W

1 kW = 1000 W

1500 W = 1.5 kW

Megawatt (MW) Examples

From the chart, we see that a megawatt is 1,000,000 x 1 W. This means that for every 1 MW, I have 1,000,000 W. So, if I have 2 MW, I have 2,000,000 W. Below are some examples of MW. Calculate your value, and then mouse over the black box to see if you are correct.

 | Formulas |
W * 1,000,000 = MW

kW* 1000 = MW

MW/ 1,000,000 = W

MW/1000 = kW

 | Examples |
1 MW = 1000 kW = 1,000,000 W

500,000 W = = 500 kW = 0.5 MW

0.01 MW = 10 kW = 10,000 W

Frequency

Hertz (Hz) Examples

The unit for frequency is hertz or Hz. Units for Hz are typically in Hz or kHz. Below are some examples, as well as formulas, for how to change units. Calculate your value, and then mouse over the black box to see if your correct.

 | Formulas |
Hz /1000 = kHz

kHz * 1000 = Hz

 | Examples |
 | 1000 Hz = 1 kHz60 Hz = 0.06 kHz |

Time

Second (sec) Examples

Common units for time are seconds (sec), milliseconds (msec) or microseconds (µsec). Below are some examples. Calculate your value, and then mouse over the black box to see if you are correct.

 | Formulas |
sec * 1000 = msec

msec / 1000 = sec

 | Examples |
1 sec = 1000 msec

500 msec = 0.5 sec

5000 msec = 5 sec

Microsecond (µsec) Examples

 | Formulas |
sec *1,000,000 = µsec

µsec / 1,000,000 - sec

msec * 1000 = µsec

µsec / 1000 = msec

 | Examples |
2 sec = 2000 msec = 2,000,000 µsec

500 µsec = 0.5 msec = 0.005 sec

Another way to calculate units is by shifting the decimal place. To go from standard units to kilo, you move the decimal 3 places to the left. To return from kilo back to standard, you move 3 places to the right. For example, If you have 1000.0 W, move decimal 3 places to the left to get 1 kW.

Select from the drop-down box to see units and the number of decimal places moved.

Unit | Move
Kilo | 3 deicmal places
Mega | 6 decimal places
milli | 3 decimal places
micro | 6 deicmal places

To move from kilo to mega, the difference between 6 and 3 is 3. Therefore, you only have to move 3 decimal places.

Another method for switching units is using the exponent. The exponent is the original number multiplied by 10 to the exponent. For example, 1 kΩ x 10^3 = 1000 Ω.

Below is a table of exponents used to change units.

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