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Current through an electromagnet

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Lesson details

Lesson outcome

Waxaan qorsheyn karaa tijaabo si aan u tijaabiyo xoogga elektromagnetic-ka waxaanan sharxi karaa sida arrimo kala duwan u saameeyaan xoogga elektromagnetic-ka.

Introduction

In this lesson: I can plan an experiment to test the strength of an electromagnet and explain how different factors affect the strength of an electromagnet. The more turns of wire in the coil of an electromagnet, the stronger its magnetic field. The greater the current through the coil of an electromagnet, the stronger its magnetic field.

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The more turns of wire in the coil of an electromagnet, the stronger its magnetic field. The greater the current through the coil of an electromagnet, the stronger its magnetic field. The more closely spaced the coils of wire of an electromagnet, the stronger its magnetic field. An electromagnet made from bare wire will not work if adjacent turns are touching. A soft iron core increases the strength of an electromagnet because it becomes magnetised when it is turned on.

Worksheet

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Quizzes

  1. 1. Which of the following statements about an object made of a magnetic material are correct?

    • Correct answer:It could be used to make a magnet.
    • It has a north–seeking pole and a south–seeking pole.
    • It is attracted to all other objects made of magnetic material.
    • Correct answer:It experiences a force when there is a magnet nearby.

  2. 2. A pupil moves two pieces of metal towards each other and they attract each other by a magnetic force. Which of the following statements are correct?

    • Correct answer:Both pieces could be magnets.
    • Correct answer:One piece could be a magnet and not the other.
    • Neither piece could be a magnet.
    • Correct answer:Both pieces must be made of a magnetic material.

  3. 3. A pupil moves two pieces of metal towards each other and they repel each other by a magnetic force. Which of the following statements are correct?

    • Correct answer:Both pieces are magnets.
    • Only one piece is a magnet.
    • Neither piece is a magnet.
    • Correct answer:Both pieces are made of magnetic material.

  4. 4. An electromagnet has a coil of wire wrapped around an iron core. A current flows in the wire. Which of the following statements explains why the electromagnet behaves like a magnet?

    • A magnet is used to make the core.
    • The wires are made of a magnetic material.
    • Correct answer:There is a magnetic field around the current–carrying wire.
    • The wire gets hot, which heats the core and makes it magnetic.

  5. 5. Which of the following would decrease the strength of an electromagnet’s magnetic field?

    • Correct answer:reducing the current in the coil
    • reducing the resistance of the coil
    • increasing the number of turns (loops) in the coil
    • Correct answer:replacing the iron core with a wooden core

  6. 6. Which of the following statements are correct?

    • Correct answer:An electromagnet can attract a magnet.
    • Correct answer:An electromagnet can repel another electromagnet.
    • Only one end of an electromagnet can pick up iron paperclips.

  1. 1. Which of the following statements describes a fair test?

    • An experiment that has an independent variable.
    • An experiment that gives accurate and reliable results.
    • An experiment that gives the same results each time it is repeated.
    • Correct answer:An experiment in which the experimenter changes only one variable.

  2. 2. A pupil tests how the strength of an electromagnet’s magnetic field is affected by the current in its coil. What is the independent variable in this experiment?

    • Correct answer:current in the coil
    • number of turns in the coil
    • strength of the magnetic field
    • material the core is made from
    • number of paperclips the electromagnet can pick up

  3. 3. A pupil tests how the strength of an electromagnet’s magnetic field is affected by the current in the coil. Which of the following are control variables in this experiment?

    • strength of the magnetic field
    • current in the coil
    • Correct answer:number of turns in the coil
    • Correct answer:material the core is made from
    • number of paperclips the electromagnet can pick up

  4. 4. Electromagnets typically have a core made of pure iron inside the coil, known as a soft iron core. What does ‘soft’ mean when describing the iron core?

    • The iron is easy to bend.
    • The iron is hard to bend.
    • The iron remains magnetised after the current is switched off.
    • Correct answer:The iron becomes demagnetised after the current is switched off.

  5. 5. A pupil wants to make an electromagnet. They wrap bare wire around an iron core and pass a current through the wire. Why does their electromagnet not work?

    • Correct answer:It has a very weak magnetic field.
    • The coils are repelled by the core.
    • The coils of wire melt and stick to the core.
    • Correct answer:Current does not go around the turns of the coil.

What pupils see

The same lesson as a pupil sees it. You can set any section as work on its own.

  • IntroductionPrepare
  • Starter quizActivate · 6 questions
  • Lesson videoLearn
  • Exit quizCheck · 5 questions
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