Topic 4: Electricity and magnetism Flashcards
(27 cards)
What are the forces between magnetic poles?
Like poles repel; opposite poles attract.
What is the difference between a magnetized and unmagnetized material?
A magnetized material has aligned magnetic domains, while an unmagnetized material has randomly aligned domains.
What is the region in which a magnetic pole experiences a force called?
A magnetic field.
What is induced magnetism?
When a magnetic material becomes magnetized temporarily when placed in a magnetic field.
How do permanent magnets differ from electromagnets?
Permanent magnets are made of steel and maintain their magnetism, while electromagnets are made by running current through a coil of wire.
What are the types of electric charges?
Positive and negative charges.
What is electrostatic charging by friction?
The process where electrons are transferred between two materials, causing one to become negatively charged and the other positively charged.
What is the difference between electrical conductors and insulators?
Conductors allow the flow of electricity, while insulators do not.
What is electric current?
The flow of electric charge, measured in amperes (A).
What is the difference between direct current (d.c.) and alternating current (a.c.)?
In d.c., the current flows in one direction, while in a.c., the direction of flow alternates.
What is the purpose of an ammeter?
To measure the electric current in a circuit.
What is electromotive force (e.m.f.)?
The work done by a source in moving a unit charge around a complete circuit.
What is potential difference (p.d.)?
The work done by a unit charge when moving between two points in a circuit.
How are voltmeters used in circuits?
Voltmeters measure the potential difference between two points in a circuit.
How is resistance related to voltage and current
Resistance (R) = Voltage (V) / Current (I).
How does the resistance of a conductor change with length and cross-sectional area?
Resistance is directly proportional to length and inversely proportional to cross-sectional area.
What is the role of a fuse in a circuit?
A fuse protects a circuit from excessive current by breaking the circuit when the current is too high.
What is the function of a switch in a circuit?
A switch controls the flow of current by opening or closing the circuit.
What is the current like in a series circuit?
The current is the same at every point in a series circuit.
What happens to the total resistance in a series circuit?
The total resistance is the sum of the individual resistances.
What is the advantage of connecting lamps in parallel?
Each lamp operates independently, and if one lamp fails, the others continue to work.
Why is it important for an electrical appliance to have a non-conducting outer casing or be earthed?
To prevent electrical shocks from the metal parts of the appliance.
What is the heating effect of current?
When current flows through a conductor, it generates heat due to resistance.
How is an e.m.f. induced in a conductor?
By moving the conductor across a magnetic field or by changing the magnetic field linking the conductor.
