Electricity (10) Flashcards
What are the differences between series and parallel circuits?
Series:
All the components are connected in a line; if one component is disconnected, the circuit is broken and current cannot pass through it. The current is the same all throughout the circuit whereas voltage is shared between components.
Parallel:
Each component is individually connected to the energy source; if one component is disconnected, current can still pass through the circuit. The potential difference is the same across all components whereas current is shared between branches.
What is potential difference?
The energy transferred per unit charge (E = Q x V). It is the driving force of charge.
What is current?
The rate of flow of charge (Q = I x t). The current in metals is the flow of electrons.
What happens when you increase the resistance in a circuit?
Increasing the resistance decreases the current as their relationship is indirectly proportional (V = I x R).
What happens when you add resistors in series and parallel circuits?
Series:
The potential difference across each resistor is lower as p.d is shared meaning the current is lower. Because current is the same across the whole circuit, the total resistance is higher across the whole circuit.
Parallel:
Both resistors have the same amount of p.d. By adding another branch, the current has more than one way to go increasing the total current that can flow around the circuit meaning a lower resistance.
How can you construct a series circuit for testing?
Connect a battery or cell in series with an ammeter and the component you want to test with a voltmeter parallel to it. Then vary the output p.d and record the voltmeter and ammeter readings.
Explain the iv graph for different components.
Filament lamp:
F-shaped graph passing through the origin. It is a non-linear graph.
LED:
Infinitely high resistance in one direction so there is an asymptote on the minus half but very low resistance in the other direction so it curves up fast. It is a non-linear graph.
Resistor:
Linear graph passing through the origin.
How does the resistance of an LDR/thermistor change with light intensity/temperature?
As light intensity/temperature increases, resistance decreases.
What happens when a component gets hot?
As a component gains thermal energy, some is transferred as kinetic energy to the ions inside the component. As the ions vibrate, they are more likely to be collided with by electrons passing through, therefore increasing resistance.
What is power?
Energy transferred per second. (P = E/t)
How is power transfer related to p.d and current?
P.d tells you how much energy each unit of charge transfers and current tells you how much charge passes per unit time so both will affect the rate that energy is transferred to the appliance. (P = I x V) and (P = I^ x R).
