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प्रश्न
Choose any one machine or device and prepare a short note about it. It should include
- The structure of the device
- How it works (functions)
- A labelled diagram
- One or two lines about when and how it evolved.
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उत्तर
- An electric bell comprises an electromagnet, a switch, a soft iron bar connected by a spring, a contact screw, a striker and a metal gong.
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- An electric bell is a mechanical bell that functions by means of an electromagnet.
- An insulated copper wire (coil) is wound around the iron core.
- When the switch is pressed, the circuit is completed, and the electric current flowing through the coil transforms the iron core into an elector magnet.
- The soft iron bar and striker are drawn to the electromagnet. The striker hits the gong, causing a sound.
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- In 1823, William Sturgeon invented an oscillating electromagnetic device that led to the development of the electric bell.
- In 1850, John Miranda added a clapper (striker) and a gong to transform it into a regular electric bell.
- Modern electric bell consists of a contact breaker (switch) to break the current.
APPEARS IN
संबंधित प्रश्न
Write what is implied in the following sentence.
But few know his inspirational life story, which is all about courage and fighting against the odds.
(What does it tell you about Faraday’s life?)
Break the passage into convenient smaller sections.
Give sub-headings or titles to each section.
List the different gadgets and instruments mentioned in the passage. Find more information about them (at least 3), using the internet.
Find out more about the following scientist with the help of the internet.
Michael Faraday
Think of as many examples of the following as you can within five minutes and write them in the appropriate column.
| Type of machine | Examples |
| Simple machines that are operated by hand |
|
| Machines that run on electricity | |
| Electronic devices |
Write as many uses of the following as you can. Form groups of four. Compare your lists. Make a long list by putting together the lists of all members.
- A cloth bag
- a wicker basket
- a glass bottle or jar
- a steel bowl
- a thick string or rope
Before you read further, guess what the passage is about.
What were the odds against Faraday in his childhood?
What is the meaning of:
Reading became his obsession?
What was the subject of Davy’s lecture?
An induction motor is a commonly used electrical machine. What examples of its use are given here?
Give one example to show that Davy was not a good mentor.
Guess the meaning of reverse engineer it.
Faraday kept a souvenir of his failure as a source of inspiration.
Write the idea behind an electrical generator.
‘In order to succeed, your desire for success should be greater than your fear of failure’.
- Michael Faraday
Why were Faraday’s drawings not accepted?
Does it mean they were wrong?
Find the following matter in the passage and copy the missing word.
People started telling Davy that ______ discoveries, ______.
Now complete the following sentence using your own word.
He decided that ______.
Now complete the following sentence using your own word.
He never believed ______.
Now complete the following sentence using your own word.
People started telling ______ that ______.
Now complete the following sentence using your own words.
He handed him ______ which ______.
Now complete the following sentence using your own word.
It was ______ who ______.
