Magnetism and electromagnetism

• What are the two types of magnetic poles? [2] - North ( seeking) pole - South ( seeking ) pole
• Where is the magnetic forces the strongest? At the pole of a magnet
• What will the north pole of a magnet attract to? The south pole of another magnet
• What will the north pole repel? The north pole will repel a north pole of another magnet
• What will a south pole repel? A south pole of another magnet
• What is the region around a magnet, where a force acts on another magnet or magnetic material called? Magnetic field
• What does the strength of a field depend on? [2] On the distance from the magnet It is strongest at the poles
• What do permanent magnets produce? Their own magnetic field
• When do induced magnets become a magnet? When they are placed in a magnetic field.
• What happens when induced magnets are removed from a magnetic field? They lose their magnetism quickly
• What is the force between a permanent magnetic and magnetic material or induced magnet always? One of attraction
• What do the arrows on a field line always run from and to? The arrows on field lines always run from north to south
• What do the arrows on the field lines show the direction of? The force that would act on a north pole placed at that point
• What is the flux density? The density of the field lines
• What does the flux density indicate? The strength of the field at that point
• What if the lines are close together in a magnetic field? Then the higher the flux density
• If the the flux indensity is high, what does this mean for the field and the force that will be felt by another magnet? The stronger the field and greater the force that would be felt by another magnet
• What does a magnetic compass contain? A small bar magnet
• What does the compass needle do in a magnetic compass? It aligns with the Earth's magnetic field and always points to the magnetic north.
• What evidence is provided if the compass needle always points to the magnetic north of the Earth's magnetic field? It provides evidence that the Earth's core must be magnetic
• What can a magnetic compass be used to plot? The field around a bar magnet
• How can you investigate how the magnetic compass be used to plot the field around a bar magnet? [6] 1. Place the bar magnet on a piece of paper 2. Place the compass at one end of the magnet 3. On the paper, mark where the point of the compass needle is 4. Move the compass, so the tail of the needle is at the point that has been marked 5. On the paper, mark a new point where the needle is 6. Repeat and connect the marks until the full field is plotted
• What happens whenever a current flows in a conducting wire? A magnetic field is produced around the wire
• What does the direction of the field lines depend on? The direction of the current
• How can the you carry out the right hand grip method? [2] - Grip the wire in your right hand, with the thumb pointing in the direction of the current. - The fingers curled around the wire will point in the direction that the field lines should be drawn
• What does the strength of the field depend on? The size of the current and the distance from the wire
• How can you see the effect of the strength of the field as it depends on the size of the current and distance from the wire? By placing a magnetic compass at different points along the wire and turning the power supply off
• How is a solenoid formed? When a wire is looped into a cylindrical coil
• What increases when shaping the wire into a solenoid? The strength of the magnetic field
• What is created when shaping the wire into a solenoid, that increases the strength of the magnetic field? It creates a strong uniform field inside the solenoid
• How can you increase the field strength further? By adding an iron core,
• When is created when you add a iron core to increase the field strength further? Electromagnet
• Why does the solenoid increase the magnetic field strength? [2] - It concentrates a longer piece of wire into a smaller area - Looped shape means that magnetic field lines around the wires all in the same direction
• What does the magnetic field around a solenoid have a similar shape to? Of a bar magnet
• How can the north pole of a solenoid be found with the right hand grip method? [2] - Hold the solenoid in your right hand with your fingers following the direction the current flows - Thumbs will point to the north pole of the solenoid
• What do many devices use? Electromagnets
• How does an electric bell work? [5] 1. When the swtich is pushed, the electromagnet is magnetised 2. The electromagnet attracts the armature 3. The hammer strikes the gong and breaks the ciruit 4. The armature springs back, completing the circuit again and remagnetising the electromagnet 5. The cycle repeats for as long as the button remains pushed
• What is the motor effect? When a current carrying conductor is placed in a magnetic field it experiences a force.
• What is the motor effect caused by? The field created by the current interacting with the magnetic field
• How can the force be increased by? [3] By increasing either: - size of the current - Length of the conductor in the magnetic field - Flux density