physics

John A. McClelland

John A. McClelland is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand John A. McClelland rather than just read about it. In short: John Alexander McClelland FRS (1 December 1870 – 13 April 1920) was an Irish physicist known for pioneering work on the scattering of β rays, the conductivity of gases, and the mobility of ions. Biography McClelland was the son of William McClelland of Dunallis, Coleraine and received his education at Queen's College, Galway.

Key takeaways

John A. McClelland belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect John A. McClelland to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of John A. McClelland from memory before moving on to harder problems.

Reference excerpt

John Alexander McClelland FRS (1 December 1870 – 13 April 1920) was an Irish physicist known for pioneering work on the scattering of β rays, the conductivity of gases, and the mobility of ions.

Biography McClelland was the son of William McClelland of Dunallis, Coleraine and received his education at Queen's College, Galway. In 1895 he received a fellowship from the Royal University of Ireland and spent 1896–1900 at Cavendish Laboratory, while pursuing a research degree at Cambridge. In 1900 he was appointed Professor of Experimental Physics at University College, Dublin. Among his other posts McClelland served as a Commissioner of National Education, a member of the Senate of the National University of Ireland and, in 1907, secretary to the Royal Irish Academy. During World War I he served as a member of the Inventions Committee and the Committee for Organisation in Industrial Research. In 1909 he was elected a Fellow of the Royal Society and in 1917 was awarded the Boyle medal of the Royal Dublin Society. In 1901 married Ina Esdale. They had five children. John A. McClelland died on 13 April 1920.

References

"Library Archive". Royal Society. Retrieved 10 February 2013.

Worked examples

Example 1 — a first encounter with John A. McClelland

Start with the simplest possible case. Write down what John A. McClelland claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to John A. McClelland before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about John A. McClelland ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of John A. McClelland

In research: John A. McClelland appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses John A. McClelland in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: John A. McClelland is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1870 births, 1920 deaths, 19th-century Irish physicists, so understanding it makes those chapters shorter.
In everyday life: Look for John A. McClelland outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study John A. McClelland in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what John A. McClelland means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain John A. McClelland out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is John A. McClelland in simple terms?

John Alexander McClelland FRS (1 December 1870 – 13 April 1920) was an Irish physicist known for pioneering work on the scattering of β rays, the conductivity of gases, and the mobility of ions. Biography McClelland was the son of William McClelland of Dunallis, Coleraine and received his education…

Why does John A. McClelland matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study John A. McClelland?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on John A. McClelland.