Starter quiz
- Which of the following instruments can show whether you are facing north?
- ruler
- compass ✓
- protractor
- pointer
- trundle wheel
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- Which of the following statements are correct?
- All metal elements are magnetic materials.
- Most metal elements are not magnetic materials. ✓
- All alloys (mixtures of metals) are magnetic materials.
- Some alloys (mixtures of metals) are magnetic materials. ✓
- Some non–metal elements are magnetic materials.
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- Which of the following would be attracted to the north–seeking pole of a magnet?
- the north–seeking pole of another magnet
- the south–seeking pole of another magnet ✓
- a piece of unmagnetised steel ✓
- a negatively charged piece of plastic
- a positively charged piece of plastic
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- Which of the following statements are correct?
- Earth has a north–seeking pole near its geographic North Pole (in the Arctic).
- Earth has a south–seeking pole near its geographic North Pole (in the Arctic). ✓
- The north–seeking pole of a magnet is attracted towards geographic north. ✓
- The south–seeking pole of a magnet is attracted towards geographic north.
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- Which of the following statements about magnetic field lines are correct?
- Magnetic field lines are real.
- A field line of a bar magnet can have gaps in it.
- The closer together the field lines, the stronger the field. ✓
- Near the S pole of a bar magnet, the field line arrows point towards the S pole. ✓
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- What do the arrows on magnetic field lines show?
- The direction of force on a positive charge.
- The direction of force on a negative charge.
- The direction of force acting on the north–seeking pole of another magnet. ✓
- The direction of force acting on the south–seeking pole of another magnet.
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Exit quiz
- Which of the following explains why a compass is affected by a current–carrying wire made of copper?
- The wire is positively charged.
- The wire is negatively charged.
- Magnets are attracted to copper.
- There is a magnetic field around the wire. ✓
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- Which of the following are reasons why soft iron is used for the core of an electromagnet?
- It is a magnetic material. ✓
- It loses its magnetism easily. ✓
- It is a good conductor of electricity.
- It is easy to mould into the right shape.
- It strengthens the field of the electromagnet.
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- A pupil investigates the relationship between the current in an electromagnet’s coil and the number of pins the electromagnet can pick up. Which of the following are control variables?
- the size of the pins ✓
- the material of the pins ✓
- the number of pins used
- the size of the current in the coil
- the number of turns of wire in the coil ✓
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- A pupil compares the strengths of different electromagnets by counting how many paper clips each can pick up. Which of the following explains why small paper clips are more suitable than large ones?
- Larger numbers are easier to show on a graph than smaller numbers.
- They are less likely to become permanently magnetised by the electromagnets.
- Smaller differences between the strengths of the electromagnets can be measured. ✓
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- Two variables, and , are related but are not directly proportional to each other. Which of the following are possible graphs of against ?
- a curve that passes through (0, 0) ✓
- a straight line that passes through (0, 0)
- a straight line that does not pass through (0, 0) ✓
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- Which of the following describes what error bars are?
- markings that are made on the anomalous points on a graph
- lines that show the relationship between the variables on a graph
- lines that show the range of possible values of a point on a graph ✓
- rails put around experimental apparatus so that it does not fall off the table
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- When there is an electric current in a wire, there is a magnetic field around the wire.
- An electromagnet is a magnet that can be turned on with an electric current, and turned off.
- The magnetic field of an electromagnet is similar to the field around a bar magnet.
- A soft iron core in an electromagnet becomes magnetised and adds to the strength of field when the electromagnet is on.
- When there is an electric current in a coil of wire, the magnetic field around each loop adds to make a stronger field.
Common misconception
A magnetic field is the same as the electric field around a charged object.
Demonstrate that an electromagnet does not attract small pieces of tissue paper, as a balloon with a static charge can do.
Keywords
Coil of an electromagnet - is an insulated wire wound into the shape of a spring.
Turn of wire - is a single loop of wire in a coil.
Soft iron - is very pure iron that cannot be made into a permanent magnet.
Directly proportional to - describes the relationship between two variables, in which doubling the value of one variable doubles the value of the other.
Error bars - show the uncertainty of each measurement on a graph.
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