SP10 - Electricity&Circuits

Created by

Christelle Evangelista

Cards (24)

An electrical circuit is a closed loop that contains a power source like a cell and something for the electrons to flow through, represented with circuit diagrams
Common symbols in circuit diagrams:
Cell: simple version of a battery
Battery: made up of two or more cells
Filament lamp: symbol for a small light bulb
Switch: can be open or closed to disrupt or allow current flow
Key terms in circuits:
Current (i): measure of electron flow, denoted in amperes (amps)
Potential difference (v): force driving electron flow, measured in volts
Resistance (r): opposes electron flow, measured in ohms
In a circuit, current flows from the positive terminal to the negative terminal, following the convention of conventional current where current flows from positive to negative
In circuits with only wires or resistors, the resistance remains constant, resulting in straight lines on current versus potential difference graphs
Filament lamps, like light bulbs, show a curve on the graph where the resistance increases as the wire heats up due to the current flow, emitting light
Diodes allow current flow in one direction, showing current only when the potential difference is positive, with high resistance in the reverse direction to prevent current flow
Components in an electrical circuit:
Battery
Switches
Voltmeter
Ammeter
Fixed resistor
Variable resistor
Filament lamp
Motor
Diode
Thermistor
LDR
LED
Purposes of components in an electrical circuit:
Battery: provides a potential difference
Switches: allows the current flow to be switched on or off
Voltmeter: measures potential difference across a component
Ammeter: measures the current flowing through a component
Fixed resistor: provides a fixed resistance to the flow of current
Variable resistor: provides a variable (changeable) resistance
Filament lamp: converts electrical energy to light energy as a useful form
Motor: converts electrical energy to kinetic energy as a useful form
Diode: allows current to flow in one direction only
Thermistor: resistance decreases when the temperature increases
LDR: resistance decreases when the light intensity increases
LED: a diode that gives out light when current flows through it
An open switch has no connection between its terminals, so there is no flow of electricity
Electrons flow clockwise in the circuit through the cell, wires, three ammeters, and two resistors
Components in circuits can be arranged in series or parallel, with different rules for current and potential difference in each type
Series circuits have just one loop for electric current flow, and the potential difference across components in series must add up to give the cell voltage
In series circuits, the size of the current is the same at every point in the circuit, and ammeters are always connected in series with components
Parallel circuits contain more than one loop, and the potential difference across components in each branch must add up to give the cell voltage
In parallel circuits, the sum of the currents in each branch must equal the current leaving the cell
Ammeters have very low resistance to accurately measure current, while voltmeters have very high resistance to prevent current flow through them
Energy, charge, and potential difference are closely related in electrical circuits
The equation relating energy, charge, and potential difference is: E = Q x V
To calculate the charge, Q, from the current reading on the ammeter, use the equation Q = I x t
The potential difference, V, across the bulb is measured with a voltmeter, which is always connected in parallel with components
An electric current is the rate of flow of charge, with the unit of charge being the coulomb (C) and one ampere (A) equaling one coulomb of charge per second
To measure the size of the current flowing through a component, an ammeter is connected in series with the component
In a closed circuit with a source of potential difference, electric current will flow, and the current is the same at all points in a series circuit