science

Nernst effect

Nernst effect is a science 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 Nernst effect rather than just read about it. In short: In physics and chemistry, the Nernst effect (also termed the first Nernst–Ettingshausen effect, after Walther Nernst and Albert von Ettingshausen) is a thermoelectric (or thermomagnetic) phenomenon observed when a sample allowing electrical conduction is subjected to a magnetic field and a temperature gradient normal (perpendicular) to each other. An electric field will be induced normal to both.

Key takeaways

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

Reference excerpt

In physics and chemistry, the Nernst effect (also termed the first Nernst–Ettingshausen effect, after Walther Nernst and Albert von Ettingshausen) is a thermoelectric (or thermomagnetic) phenomenon observed when a sample allowing electrical conduction is subjected to a magnetic field and a temperature gradient normal (perpendicular) to each other. An electric field will be induced normal to both. This effect is quantified by the Nernst coefficient ν {\displaystyle \nu } , which is defined to be

ν = E y B z 1 ∂ x T {\displaystyle \nu ={\frac {E_{y}}{B_{z}}}{\frac {1}{\partial _{x}T}}}

where E y {\displaystyle E_{y}} is the y-component of the electric field that results from the magnetic field's z-component B z {\displaystyle B_{z}} and the x-component of the temperature gradient ∂ x T {\displaystyle \partial _{x}T} . The reverse process is known as the Ettingshausen effect and also as the second Nernst–Ettingshausen effect.

Physical picture Mobile energy carriers (for example conduction-band electrons in a semiconductor) will move along temperature gradients due to statistics and the relationship between temperature and kinetic energy. If there is a magnetic field transversal to the temperature gradient and the carriers are electrically charged, they experience a force perpendicular to their direction of motion (also the direction of the temperature gradient) and to the magnetic field. Thus, a perpendicular electric field is induced.

Sample types The semiconductors exhibit the Nernst effect, as first observed by T. V. Krylova and Mochan in the Soviet Union in 1955. In metals however, it is almost non-existent.

Superconductors Nernst effect appears in the vortex phase of type-II superconductors due to vortex motion. High-temperature superconductors exhibit the Nernst effect both in the superconducting and in the pseudogap phase. Heavy fermion superconductors can show a strong Nernst signal which is likely not due to the vortices.

See also Spin Nernst effect Seebeck effect Peltier effect Hall effect Righi–Leduc effect

References

Illustrations

Worked examples

Example 1 — a first encounter with Nernst effect

Start with the simplest possible case. Write down what Nernst effect claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Nernst effect 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 Nernst effect 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 Nernst effect

In research: Nernst effect appears in science 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 Nernst effect 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: Nernst effect is common in secondary-school and first-year university syllabi. It links to neighbouring topics Electrodynamics, Thermoelectricity, Walther Nernst, so understanding it makes those chapters shorter.
In everyday life: Look for Nernst effect 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 Nernst effect in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nernst effect 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 Nernst effect out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nernst effect in simple terms?

Why does Nernst effect matter?

Because it connects several science 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 Nernst effect?

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 Nernst effect.