science

Pull switch

Pull switch 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 Pull switch rather than just read about it. In short: A pull switch, also known as pull-cord switch, or light pull, or pull chain is a switch that is actuated by means of a chain or string. History An electric pull switch is attached to a toggle type switch: one pull to switch on and next pull to switch off.

Key takeaways

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

Reference excerpt

A pull switch, also known as pull-cord switch, or light pull, or pull chain is a switch that is actuated by means of a chain or string.

History An electric pull switch is attached to a toggle type switch: one pull to switch on and next pull to switch off. It was invented by Harvey Hubbell, who was granted its patent in 1896.

Mechanics

The most common use of a pull switch is to operate a ceiling electric light. The ceiling fan and mechanical wall fans are also appliances often operated by pull switches. Pull switches may be either two-position (open or closed) or multi-position (allowing for different fan speeds or levels of illumination). Mounted inside a pull switch, there could be two types of two-position toggle switches. (In both cases the stable physical open- or closed -situation would be switch in outer and string in upper position.) One type would switch to closed (alternatively open) already during the initial pull in the string. The other type would switch to closed (or open) only when releasing after a full pull. With the first type, the weight of the string and handle could accidentally switch the load intermittently on and off, when still around the initial position (depending on the internal spring). This could potentially increase the danger of overheating in the switch. Most commercially available pull switches use a short length of ball chain, which may then be connected to any number of optional leads for added length or decoration. Leads for decoration or utility are made of brass, acrylic, ceramic, or other materials. They can come in many different shapes ranging from geometric shapes to animals.

Illustrations

Worked examples

Example 1 — a first encounter with Pull switch

Start with the simplest possible case. Write down what Pull switch 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 Pull switch 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 Pull switch 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 Pull switch

In research: Pull switch 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 Pull switch 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: Pull switch is common in secondary-school and first-year university syllabi. It links to neighbouring topics Switches, so understanding it makes those chapters shorter.
In everyday life: Look for Pull switch 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 Pull switch in 20 minutes

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

Frequently asked questions

What is Pull switch in simple terms?

A pull switch, also known as pull-cord switch, or light pull, or pull chain is a switch that is actuated by means of a chain or string. History An electric pull switch is attached to a toggle type switch: one pull to switch on and next pull to switch off.

Why does Pull switch 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 Pull switch?

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 Pull switch.