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Article by Ella von Lieres Thorne IB12 (05.03.2026)
Every time you unlock your phone, billions of tiny switches flip on and off in less than a second. Transistors are key electronic components in most modern electronics. These are defined as devices that use electricity to process information or perform tasks. Nowadays, the 1947 innovated transistor is produced and packaged in the billions, either embedded in integrated circuits or individually. First invented at Nokia Bell Labs research and development company in New Jersey, physicists John Bardeen,Walter Brattain, and William Shockley1 allowed for our accustomed radios, calculators and modern computing to come into fruition. Of course the dirt-cheap price of each resistor contributes largely to these innovations. (Irony)
Previous machines used for calculations in atomic research in 1942, before the vacuum tube era in mid-WWII, used relays. These were electronic switches that needed tender care and replacement if worn out.2
Initially, radio telecommunication was amplified with vacuum tubes. These were comparatively janky to the transistor. Very few have good associations with vacuums and this remains constant with vacuum tubes. Large, fragile and power guzzling, the thermionic triode did not suffice.3 But alas, the trusty fieldeffect transistor (FET), a type of transistor that uses an electric field to control the current through a semiconductor, had not yet been brought to the market. Conclusively, the first computers filled entire living rooms. They weighed 30 tons and consumed 150 kW of electricity. The average European household consumes 6-8 kW per day, so roughly 25 times less than the daily median of these machines. These early computer circuits controlled currents by using a heated element that released electrons and a control grid that either allowed or blocked those electrons from reaching a positively charged plate. This effectively turned the current on or off. On top of that, one could not even transport this technology. The previously mentioned tubes frequently failed almost daily, requiring tedious manual replacement. This computer predecessor used roughly 18,000 vacuum tubes.
Society needed something significantly smaller and more reliable.
Transistors are defined as “semiconductor devices that amplify weak signals and switch current on or off”.4 To understand how these are effective, we need to observe their actions in the electric circuit. Electric current is a flow of electric charges. Most electrons are held tightly to their respective atoms and are negatively charged. In a copper wire circuit, positive ions and free electrons move through the wire with constant drift velocity. This creates the flow of charge and thereby electric current. Power circuits use resistors for voltage and current regulation. Here Ohm’s law is applied, stating that “the current through an ohmic conductor is directly proportional to the potential difference across it provided that the temperature remains constant”.5 Characteristics of ohmic conductors include constant resistance remaining unchanged to voltage and current and essentially constant temperature.
Semiconductors also significantly contribute to the flow of current and are essential for the control of this, tying in with resistor function. They are very important in electronics and allow for conductivity in a circuit to be controlled through doping (not drugs), i.e. adding N-type or donor semiconductors that have extra free valence electrons and P-type or acceptor semiconductors with missing electrons creating holes. When these P and N materials, such as arsenic and gallium, are joined they create a junction. This basically means that that region can be controlled due to its depletion.
This is where transistors come in. A transistor is a component that controls whether electric current flows or is blocked in a circuit. In simple terms, it acts like a tiny switch. When it allows current to pass it is ON. When it blocks current it is OFF.
This switching behavior connects directly to the binary numbering system, which is the foundation of computing. Binary uses only two values, 1 and 0. Inside a computer’s CPU, often called the brain, and RAM, its short-term memory, electrical signals are constantly switching between ON (1) and OFF (0). These signals tell the hardware what to do such as storing data, performing calculations, comparing values or moving information.
By organizing millions or billions of transistors together, engineers create logic gates. Logic gates are arrangements of switches that follow simple rules such as AND, OR and NOT. These gates process binary inputs and produce binary outputs. When vast numbers of logic gates are combined they form complex circuits capable of advanced data processing. This layered structure allows computers and machines to function efficiently and intelligently.
Onto how transistors actually changed society. As previously stated the mighty transistor replaced clunky, massive vacuum tubes allowing for computers to be more compact and energy-efficient, unlike the early ENIAC computers filling rooms. Modern computers use billions of transistors and present themselves as much more compact. Additionally, the transistor created microprocessors through integrated circuits with transistors controlled by semiconductors.
These are the essential chips in phones, computers and started the personal computer revolution (PC). Communication was also revolutionized.
Finally in the 1950s, portable access to news, music and broadcasts became possible through radios.
Smartphones also rely on microprocessors with billions of transistors for apps, telecommunication and cameras.
Satellites also became smaller, lighter and more reliable. Further areas of improvement and development since the 1947 discovery include cars, medical equipment, gaming systems and smart appliances. It can be stated that modern life significantly depends on the collective function of billions of these transistors working simultaneously.
The concept of integrated circuits is essential for how most of these devices are able to function. It describes that “the integration of large numbers of tiny transistors into a small chip results in circuits that are smaller, cheaper and faster than those constructed of discrete electronic components”.14 This shows the functions behind mere devices and how a small part can make a circuit and lead to exponentially furthering innovations.
Interestingly, it has been observed that the transistor density or count doubles around every two years. In 2016, the largest transistor count in a commercially available single-chip processor was over 7.2 billion. Now in 2025, the commercial transistor counts for advanced single-chip commercial microprocessors are exceeding 184 billion.
So why does this transistor component still matter? Transistors have transformed technology and society in ways that are easy to take for granted. They made computers smaller, faster, and more reliable. They enabled microprocessors, smartphones, satellites, and countless modern devices
Although transistors transformed and accelerated technological as well as societal development, they also have the key to powering our modern world. As AI data centers demand higher transistor density to improve speed and energy efficiency, such scaling needs to be thought through especially in regards to heat capacity and electricity consumption. Hopefully, this informs further about the hidden constituent behind widely used technology and sheds some light on the importance of these parts.
1 https://en.wikipedia.org/wiki/Transistor
2 https://beaver.my/the-evolution-of-electronic-computing-from-vacuum-tubes-to-transistors/
3 https://en.wikipedia.org/wiki/Transistor
4 https://techweb.rohm.com/product/transistors-diodes/transistors/23714/?utm_source=chatgpt.com
5 Pearson Physics Higher Level 2rd Edition for the IB Diploma Programme
6 https://www.electronics-notes.com/articles/basic_concepts/resistance/ohmic-nonohmic-linear-conductors. php
7 https://www.shindengen.com/products/semi/column/basic/semi/rectifying_action.html
8 https://www.researchgate.net/figure/Transistor-symbol-and-binary-interpretation-as-ON-OFF-switch-The-d igital-operation-of_fig1_340062372
9 https://www.101computing.net/from-transistors-to-micro-processors/
10 https://en.wikipedia.org/wiki/Transistor_radio
11 https://www.dreamstime.com/photos-images/cell-phone-transistor.html
12 Salut 1 18,900kg 1971 https://www.sciencefocus.com/space/top-10-heaviest-spacecraft
13 AST Spacemoblie 2022 https://www.newscientist.com/article/2446651-astronomers-worried-by-launch-of-five-new-super-bright-satellites/
14 https://www.101computing.net/from-transistors-to-micro-processors/
15 https://www.101computing.net/from-transistors-to-micro-processors/
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