5. Electricity & Magnetism Flashcards
Why can electrical charges move easily through certain substances like metals?
Electrical charges can move easily through some substances because these substances, like metals, have many free charges (electrons) that are free to move.
What is static electricity, and what happens when there is an imbalance of charge in an object or area?
Static electricity occurs when there is an imbalance of charge in an object or area. This imbalance results in a buildup of charge with no conducting route to travel along. When a conducting route is provided, the result is a discharge.
What is electric current, and how is it defined?
Electric current is the rate of flow of electric charge.
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Define voltage and potential difference in an electrical circuit.
The voltage of a source is the energy supplied by a source in driving charges round a complete circuit and is measured in volts.
Potential difference across a component measures the energy transfer by charges and is also measured in volts.
Explain the relationship between potential difference, energy transferred, and charge.
The relationship between potential difference is given by the equation:
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Explain the concept of resistance in an electrical circuit and how it affects the flow of current.
Components resist the flow of charge through them. The greater the resistance, the smaller the current for a given potential difference across the component.
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How does the resistance of a thermistor change with temperature, and what are its applications?
The resistance of a thermistor decreases as the temperature increases. Thermistors are used in circuits, such as thermostats, where their resistance changes with temperature.
What is the โforwardโ resistance of a diode, and how does it behave in an electrical circuit?
The โforwardโ resistance is low in a diode, and the โreverseโ resistance is very high. The current through a diode flows in one direction only, allowing it to act as a semiconductor in electrical circuits.
What are the strongest points of magnetic forces in a magnet?
The strongest points of magnetic forces in a magnet are at its poles.
Explain the interaction between two magnets when they are brought close together.
When two magnets are brought close together, they exert a force on each other. Two like poles repel each other, while two unlike poles attract each other.
What is a magnetic field?
A magnetic field is the space around a magnet where a force acts on another magnet or on a magnetic material like iron, steel, cobalt, or nickel.
What is an induced magnet?
An induced magnet is a material that becomes a magnet when placed in a magnetic field.
What happens to an induced magnet when removed from a magnetic field?
When removed from a magnetic field, an induced magnet loses most or all of its magnetism quickly.
What is the shape of the magnetic field lines around a wire carrying an electric current?
The magnetic field lines around a wire carrying an electric current form concentric circles in a plane perpendicular to the wire.
How does increasing the current affect the strength of the magnetic field around a wire?
Increasing the current makes the magnetic field stronger around a wire.
