technology in three

 The first (number system) digit in the 12-digit UPC Version A (Universal Product Code for North America) barcode is 3 for drugs, beauty aid and health products, (followed by 5-digit manufacturing code, 5-digit product code and 1 check digit at the right end).

 

 The number of hands on a regular mechanical clock or watch, showing hours, minutes and seconds.

 

The number of primary colors of paper printing inks (for books, magazines…) or dyes: cyan, magenta and yellow, (together with black). Mixing these 3 primary colors gives black. They are 3 secondary colors of light.

 

The number of secondary colors by mixing primary colors of paper printing inks (for books, magazines…) or dyes: red (magenta and yellow with equal amount), blue (magenta and cyan) and green (yellow and cyan). They are 3 primary colors of light.

 

The number of primary colors of light (such as for TV screen): red, blue and green. They are 3 secondary colors of pigments. Mixing these 3 primary colors of lights gives white.

 

The number of secondary colors of light (such as for TV screen): yellow (mixing red and green with equal amount), cyan (blue and green) and magenta (red and blue). They are 3 primary colors of pigments.

 

 The number of letters in the name codes for U.S. radio stations, assigned by the Radio Act in 1912. Other: 4.

  

Rule of thumb: Twice as much power or intensity of sound is measured by 3 decibels (or exactly 10×log102) decibels higher.

 

 The name “3M” stands for “Minnesota Mining and Manufacturing Company”, founded in Two Harbors, Minnesota in 1902.

 

The popular Alkaline-Manganese battery voltages for household electronic devices: 1.5V – 3V – 4.5V – 6V – 9V, available in popular sizes: AAA, AA, C, D, G and N. The Carbon-Zinc batteries have additional values: 12V – 22.5V – 45V and 90V. Other values: PP3 – 1.2V – 3.6V – 4.8V – 8.4V for Ni-Cad rechargeables.

 

 

The powers of commercial incandescent light bulbs: 300W, 100W, 75W, 60W, 40W, 30W, 15W, 7.5W and 3W.

 

Nuclear accident at Three Mile Island (near Harrisburg, Pennsylvania) occurred in 1979. (The island may be actually only 2.5-mile long).

 

The “number system” code of an EAN-13 barcode for the U.S. and Canada’s products: 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12 and 13.

 

Frequency Ranges

 

Range

Names

Uses

3 Hz –

300 Hz

Extremely Low Frequency (ELF)

Telegraph

300 Hz –

3 KHz

Voice Frequency (VF)

Telephone Circuitry

3 KHz –

30 KHz

Very Low Frequency (VLF)

High Fidelity

30 KHz- 300 KHz

Low Frequency (LF)

Maritime Mobile

300 KHz –

3 MHz

Medium Frequency (MF)

Navigational Radio, Land-maritime Mobile

3 MHz –

30 MHz

High Frequency (HF)

Maritime, Aeronautical, Amateur Radio

30 MHz –

300 MHz

Very High Frequency (VHF)

Maritime, Meteorological Communication, Television

300MHz –

3 GHz

Ultra High Frequency (UHF)

Television, Military, Low Range Radar

3 GHz –

30 GHz

Super High Frequency (SHF)

Space, Satellite, Microwave

30 GHz –

300 GHz

Extremely High Frequency (EHF)

Radio Astronomy

 

3.6

The voltage of a Ni-Cad rechargeable battery of type AA, AAA, C, D and N is usually 1.2V (less than 1.5V of non-rechargeable batteries). Other values: PP3 – 1.2V – 3.6V – 4.8V – 8.4V.

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