P4 Electric Circuits - Physics Paper1 Flashcards
State an equation that links current, charge and time
Q = IT Charge(C) = current(A) X time(S)
What is the potential diffference
The work done by each coulomb of charge that passes through a component
What’s the resistance in a circuit
Anything in a circuit which slows down the flow of the current
State an equation that links current , potential difference and resistance
V = I R Potential difference (V)= Current(A) X Resistance( Ω )
What is an ohmic conductor
In ohmic conductors, the resistance doesn’t change with the current. At a constant temperature, the current flowing through an ohmic conductor is directly proportional to the potential difference across it.
What’s the effect of the length of a wire on resistance
The longer the wire, the greater the resistance- the values are directly proportional to one another
Name one linear component and one non-linear component
A resistor is a linear component and a filament lamp is a non-linear component
Where does Ω come from?
an uppercase Greek letter omega
What are the IV characteristics of a filament lamp?
As the current increases, the temperature of the filament lamp also increases and therefore, the resistance increases as well. This means that less current can flow per unit potential difference and hence the graph gets shallower.
What are the IV characteristics of a diode?
In a diode, current will only flow in one direction. The diode has a very high resistance in the reverse direction.
What are the IV characteristics of a diode?
In a diode, current will only flow in one direction. The diode has a very high resistance in the reverse direction.
How does the resistance of an LDR vary with light intensity?
The darker it is, the higher the resistance
What happens to the resistance of a thermistor as it gets colder?
the resistance goes up
What are some uses o LDR’s
automatic night lights, outdoor lighting, burglar detectors
What happens to the resistance of a thermistor as it gets warmer
the resistance goes down
What are thermistors used for
temperature detectors in car engine temperature sensors and in thermostats
What is an LDR
A resistor that is dependent on the intensity of light
What is a thermistor
A resistor that’s dependent on temperature
What is the potential difference like in series circuits?
The potential difference of the battery is shared between the components
What is the current like in series circuits?
The current is the same for all components
What is the resistance like in series circuits?
The total resistance of the circuit is the sum of each components resistance
What is the potential difference like in parallel circuits?
The potential difference across each branch is the same as the potential difference of the battery
What is the current like in parallel circuits?
The total current is the sum of the current of each branch
What is the resistance like in parallel circuits?
The total resistance is less than the smallest resistance of the an individual branch
Why are parallel circuits more useful at home?
Because you have to be able to switch appliances on and off separately
Why does adding resistors in parallel decrease the total resistance of the circuit?
Because by adding another loop , the current has more than one direction to go in. And, by using V= IR, an increase in current results in a decrease in the total resistance of the circuit.
What does adding more resistors into a series circuit do?
Increases the total resistance, as the current decreases
