electricity (circuits) Flashcards
(23 cards)
How does metallic bonding allow electric current to be transferred around a circuit?
A sea of delocalised electrons
What is current?
The flow of electrical charge around a circuit
How is current measured?
In amps with an ammeter
What is potential difference?
The difference in energy between two points of a circuit
How is potential difference measured?
In volts with a voltmeter
What is resistance?
Something that slows down the current
What is resistance measured in?
Ohms
How do you work out resistance in a series circuit?
Rtotal = R1 + R2 + …
How do you work out resistance in a parallel circuit?
The total resistance of two resistors is less than the resistance of the smallest individual resistor.
What happens in a circuit if PD is constant?
The current is decreased as the resistance is increased
What is Ohm’s Law?
Current is directly proportional to potential difference if temperature is constant
What are the features of series circuits?
-All components are connected by one loop
-If one bulb breaks, the whole circuit stops
-Current is the same everywhere
-The potential difference is shared between components
-The total resistance is the sum of the individual resistances
-The more bulbs added, the dimmer they become
What are the features of parallel circuits?
-All components are connected by multiple loops
-If one bulb breaks, the other branches continue
-Current is the shared between each branch
-The potential difference is the same between each branch
-The total resistance is less than the smallest individual resistance
If bulbs are added, the brightness stays the same
What are the features of an ohmic conductor?
-Resistance remains constant when current is changed
-Current is directly proportional to potential difference
Give an example of an ohmic conductor
A resistor at a constant temperature
Give an example of a non-ohmic conductor
A filament lamp; resistance increases as heat increases (s curve)
A diode; current can only flow in one direction so resistance is very high the other way (straight horizontal line to diagonal line)
What is the relationship of an LDR?
light intensity = 1/distance^2 (inverse square)
What is an example of an LDR?
Lana Del Rey
(and street lights ig)
What is the relationship of a thermistor?
Resistance decreases, temperature increases (inversely proportional)
What is an example of a thermistor?
Thermostats
