🔌 • Lesson 3.7 : Electrical Circuits (Phys) Flashcards
In this long lesson, you will master knowledge concerning series and parallel circuits, learn electrical safety, rediscover electromagnetic effects and induction, current, generators, conductors, motors and transformers. (31 cards)
How does the current behave in a series circuit?
The current at every point in a series circuit is the same.
What is the combined resistance of two resistors in series?
The combined resistance is the sum of the individual resistances.
How does the current behave at a junction in a parallel circuit?
The sum of the currents entering a junction is equal to the sum of the currents leaving the junction.
How does the potential difference (p.d.) behave in a series circuit?
The total p.d. across the components is the sum of the individual p.d.s across each component.
How does the potential difference (p.d.) behave in a parallel circuit?
The p.d. across each branch of a parallel arrangement is the same as the p.d. across the whole arrangement.
What are the advantages of connecting lamps in parallel?
Lamps in parallel ensure that each lamp has the same voltage, and if one lamp fails, others remain lit.
How does the current behave in a parallel circuit?
The current from the source is larger than the current in each branch.
How does the combined resistance of two resistors in parallel compare to the resistance of each resistor?
The combined resistance of two resistors in parallel is less than that of either resistor by itself.
How do you calculate the combined resistance of two resistors in parallel?
R total = (R1 x R2)/(R1 + R2)
R1 and R2 stand for the resistances of the individual resistors.
What is the heating effect of current?
When current flows through a conductor, it causes the conductor to heat up due to the resistance to the flow of electrons.
What are the hazards of damaged insulation?
Can lead to electrical shocks, short circuits, or even fires by allowing current to escape or contact conductive materials.
What are the hazards of overheating cables?
Can cause fires by melting the insulation and allowing electrical contact with other surfaces, creating sparks or overheating.
What are the hazards of damp conditions?
Damp conditions can increase the risk of electrical shocks by lowering the resistance of the body, allowing more current to flow through it.
What are the hazards of excess current from overloading plugs, extension leads, and sockets?
Overloading causes excessive current, which can overheat cables, damage appliances, and increase the risk of fire or electrical shock.
How do trip switches and fuses work to protect electrical systems?
They protect circuits by **cutting off*8 the current when it exceeds safe levels, preventing overheating, damage, or fire.
How do you choose appropriate fuse ratings and trip switch settings?
Choose based on the appliance’s power rating and circuit wiring.
Example: a 1000W appliance at 230V requires a fuse rated for at least 4.35A (1000W ÷ 230V).
How is an induced e.m.f. created?
Moving a conductor through a magnetic field or changing the magnetic field around a conductor induces an e.m.f. across it.
What factors affect the magnitude of an induced e.m.f.?
The speed of movement, strength of the magnetic field, and the number of coils in the conductor affect the induced e.m.f.
What is a simple a.c. generator and how does it work?
A simple a.c. generator consists of a rotating coil in a magnetic field, using slip rings and brushes to transfer current.
How do you sketch a graph for an a.c. generator?
The graph of e.m.f. against time is a sinusoidal wave, with alternating peaks and troughs.
What is the magnetic field pattern around straight wires and solenoids?
The magnetic field around a straight wire forms concentric circles; around a solenoid, it forms uniform parallel lines.
How does current change affect the magnetic field around wires and solenoids?
Increasing current strengthens the magnetic field, and reversing current reverses the field direction.
What happens when a current-carrying conductor is in a magnetic field?
A force acts on the conductor, and the direction of the force can be changed by reversing the current or the magnetic field direction.
How are force, magnetic field, and current related?
They are related by the right-hand rule, where the thumb points to the current, and fingers point to the magnetic field.
