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Which way do magnetic field lines point?
North pole to south pole
South pole to north pole
True or false? An electromagnet is a piece of insulated wire wrapped around an iron core which can be temporarily magnetised if current flows through it.
Which of these devices make use of electromagnets?
What does the first finger stand for in Fleming's left-hand rule of the motor effect?
Direction of force
Direction of field lines
Direction of current
True or false? The device used to make a motor spin without tangling its wires is called a switch-mode commutator.
True or false? A loudspeaker produces sound when a coil is repeatedly moved back and forth by the motor effect.
Which scientist discovered electromagnetic induction?
How can we reverse the direction of the force in the motor effect?
Reverse the magnetic field lines
Reverse the direction of the current
Reverse the direction of the current and the magnetic field lines
Use alternating current instead of direct current
True or false? A potential difference is induced across a wire when it is moved to cut across magnetic field lines.
True or false? An induced potential difference will never lead to an induced current.
How many coils of wire does a transformer have?
Which transformer has fewer turns on the secondary coil than on the primary coil?
True or false? Transformers only work when a direct current is passed through them.
What is the core of a switch-mode transformer made of?
True or false? Having a higher voltage in transmission cables reduces I^2R losses and so conserves as much energy as possible.
What is the potential difference across the primary coil of a transformer if the primary coil has 60 turns, the secondary coil has 20 turns and the potential difference across the secondary coil is 150V?
What is the current across the secondary coil of a transformer if the current across the primary coil is 4A, the potential difference across the primary coil is 600V and the potential difference across the secondary coil is 800V?
Which of these is used to record potential difference?
Blood pressure gauge
True or false? MRI stands for magnetic resonance imaging.
True or false? MRI is an ionising form of imaging, while CT scanning is not.