Rotary Dial - What's That? Quiz / Test | History of Science

Quiz Answer Key and Fun Facts

1. The rotary dials in the quiz title were attached to telephones before they had key pads. They were used to transmit the digits you wanted to dial to the telephone exchange. But how did they work?

Answer: They sent a fixed number of electric pulses for each digit

You put your finger in the hole in the dial and turned it until you reached a stop. When you released it, a spring pulled it back and sent electrical pulses to the telephone exchange. In North America, there was one pulse for the digit "1", two for "2" and so on up to ten pulses for "0". But there were other solutions: in Sweden, it was instead one pulse for "0", two pulses for "1" and so on up to ten pulses for "9" and in New Zealand the number of pulses sent was ten minus the number dialled.

The rotary dial was replaced by a system called dual-tone multi-frequency (DTMF) where each key on the key pad sent two tones: one for the row and one for the column.

2. For a long time, almost all cars running on gasoline had carburetors. What was the purpose of them?

Answer: To mix air and fuel droplets

Gasoline (petrol) doesn't burn easily or effectively unless it's dispersed into tiny droplets and mixed with air. Too few droplets in the mix and the engine starves; too many and the engine can't burn all of them. The role of the carburetor was to mix the fuel with air in a correct mixture. That mix can then be sucked into the cylinder, be compressed by the piston and ignited by the spark plug. Today, the technology used for this purpose is the fuel injector that uses high pressure and a nozzle to achieve the same effect. Diesel engines never had carburetors: they've always been fuel-injected.

3. Does anyone remember the compact cassette tape where you could record audio? They were introduced in the 60s and almost everyone in the 70s/80s had at least one player: stationary, portable or mounted in the car. The cassettes could be labelled C60, C90 or C120. What did those numbers stand for?

Answer: Total recording time

The cassettes were reversible, so a C90 cassette had two sides that each could record 45 minutes. That was practical, since most LP records contained 40-45 minutes of music. To fit in the same cassette, C120 tapes were much thinner than C60 tapes and therefore more prone to break or tangle. I used C60 for mixed tapes and C90 for copying complete albums.

There were codes for the material in the magnetic coating, too, and there was much debate whether Fe (Iron) or Cr (Chrome) tapes were the best.

4. Some inventions are for the ages. A device that consists of a cylinder with a screw inside has been used to pump water for irrigation since ancient times and is still in use. It's usually attributed to which Greek, who described it after a visit to Egypt?

Answer: Archimedes

It seems as if most Bronze Age inventions are attributed to Archimedes. In the case of the Archimedes's screw, it's very possible an Egyptian invention documented and popularized by him. The screw is still used in its original form, for example in Egypt, but the idea is used in modern design as well, such as in combine harvesters.

Archimedes was Greek, but was born, lived and worked in Sicily, which at the time had Greek settlements.

5. An invention that revolutionized the farming industry of the American South in the early nineteenth century is the "mechanical gin", the brainchild of American inventor Eli Whitney. For which crop was it designed?

Answer: Cotton

The purpose of a cotton gin is to remove the little seeds from the white fiber. It was a very labor intensive task and made it difficult to make cotton plantations profitable, even with slave labor. In the beginning of the nineteenth century, cotton yields doubled each decade when earlier types of gin were replaced.

Why is it called a "gin"? It's simply short for "engine".

6. Show a video tape from the 1970s-1990s to a child today and they have no idea what it is. Perhaps the same will be true about CDs and DVDs in the not-so-far-away future? Before the market decided that VHS was the way to go, there were other systems available such as Betamax from Sony and which technology from Dutch manufacturer Philips and German company Grundig?

Answer: Video 2000

Launched in 1979, Video 2000 (or "V2000") had some innovative features the competition lacked, but alas it came out too late. Sony (Betamax) and JVC (VHS) were already battling it out for supremacy and V2000 was only ever released in Europe and a few smaller markets.

It was discontinued in the late 80s. As some of us remember, VHS won out over Betamax and ruled supreme until the advent of the DVD.

7. The time it takes for a product to go from being new to becoming obsolete gets shorter all the time, sometimes because of technology shifts, but these days often because people get tired of them. A "tamagotchi", hugely popular for a short few years in the late 90s and early 00s, was what kind of toy?

Answer: Electronic pet

The Japanese egg-like toy had a simple pixel animation of a pet that required you to feed it, play with it, etc. I lived in Japan at the peak of the hype, and most women in their twenties and thirties had (at least) one. Some spent more time in the office playing with the tamagotchi than doing actual work until suddenly nobody used them anymore.

8. "Ticker tape parades" used to be a thing. During such parades in, most famously, New York, the object of the festivities was showered with "ticker tapes": long, thin ribbons of paper. But what were they really used for?

Answer: Print stock prices

Ticker tape machines were telegraph receivers that automatically printed the abbreviation of a stock and the latest market price. It's referred to as the earliest digital communications medium and was in use for about a hundred years from 1870. They could also be used for other information such as sports results. Have you seen the 1973 movie "The Sting"? A ticker tape machine that receives the results of horse races plays a major role in the plot.

During ticker tape parades, office workers threw used ticker tapes over homecoming heroes and politicians.

9. Up until the late eighteenth century, many rich families in Europe had a harpsichord. What was that?

Answer: Musical instrument

If you think about Baroque music at all, you probably think of the slightly metallic sound of the harpsichord. Even later composers, such as Mozart, wrote music for the harpsichord. After the invention of the piano, which gave the musician more possibilities to play soft and loud, the harpsichord was gradually replaced. It's still used to play period music.

10. Vacuum tubes were first built in 1904 and were at the forefront of technology. Since the advent of the flat screen TV, most of us no longer come across them very often. What was the first application using vacuum tubes? It heralded the rise of the electronic age.

Answer: Diodes

Vacuum tubes were indeed used in amplifiers, and some people think they sound better than modern amplifiers built on transistors. The first application was however as a simple diode: a device that lets current flow in one direction but not in the other. Other, new, electronic components followed and were used in early computers.

With the arrival of semi-conductor based solid state components such as the transistor, vacuum tubes quicky became obsolete in electronics. Their use as cathode ray tubes in television sets and computer monitors continued until quite recently.

Source: Author akg1486

This quiz was reviewed by FunTrivia editor rossian before going online.
Any errors found in FunTrivia content are routinely corrected through our feedback system.

Rotary Dial - What's That? Trivia Quiz

All tech gadgets go through the same cycle: from cutting edge to everyday to obsolete and perhaps even forgotten. If you're young, you may not have used some of these once-high-tech inventions.

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