Section 5 - Electricity and Circuits Flashcards
(40 cards)
What is current?
The flow of electrical charge.
What is potential difference?
The driving force that pushes the charge around, the energy transferred per unit charge that passes between two points in a circuit.
What is resistance?
Anything that slows the current down.
What is the equation for charge?
Q=I×t
Q = Charge I = Current t = Time
What are some necessary circuit components?
Cell Battery Open switch Closed switch Filament lamp Fuse LED Power supply Resistor Variable resistor Ammeter Voltmeter Diode LDR Thermistor Motor Wire
Describe the equation relating potential difference, current and resistance.
V=I×R
V = Potential difference I = Current R = Resistance
Describe the normal trend between temperature and resistance.
As temperature increases, so does resistance.
What is an ammeter? How is it installed in a circuit?
It is a device that measures current, it must be installed in series as part of the main circuit.
What is a voltmeter? How is it installed in a circuit?
It is a device that measures potential difference, it must be installed in parallel to another circuit device.
What is a diode?
A device that only allows current to flow through it one way.
What is an LDR?
A device that changes its resistance in response to changes in light level.
What is a thermistor?
A device that changes its resistance in response to changes in temperature.
What is the trend between light and resistance in LDRs?
As light levels increase, resistance decreases.
What is the trend between temperature and resistance in thermistors?
As the temperature increases, resistance decreases.
What is a series circuit?
A circuit in which every device is connected to the next in one loop.
What is a parallel circuit?
A circuit in which devices may be connected to others in multiple loops. This makes the separate loops independent.
How does adding a resistor to a series circuit affect its total resistance?
It increases it.
How does adding a resistor to a parallel circuit affect its total resistance?
It decreases it.
Describe the equation relating energy transferred, voltage, current and time?
E=I×V×t
E = Energy transferred I = Current V = Voltage t = Time
What is the normal trend between current and temperature?
As the current increases, more energy is transferred to the thermal energy stores of the components, this increases temperature.
Describe the trend between heat and efficiency.
As heat increases, efficiency decreases.
What are some uses of heating in electronics?
Fuses, ovens, toasters, heaters and filament bulbs.
What is power?
A measure of how much energy is transferred per second.
What are the equations for power?
P=E/t
P=I×V or P=I²×R
P = Power E = Energy transferred t = Time V = Potential difference R = Resistance I = Current
