P2: I,V,R + SERIES AND PARALLEL CIRCUITS Flashcards
What is current?
the rate of flow of charge
What’s the difference between direct current and alternating current?
-direct current (dc) only flows in one direction
-alternating current (ac) constantly changes direction
What equation links current, charge and time?
current (A) = charge (C) / time (s) (I = Q/t)
What is potential difference/voltage?
the amount of energy transferred per unit charge
What equation links energy, voltage and charge?
energy (J) = voltage (V) x charge (C) (E = VQ)
What is resistance?
how difficult it is for current to flow
What equation links current, voltage and resistance?
voltage (V) = current (A) x resistance (Ω) (V = IR)
What happens to current in a series circuit?
it stays the same throughout the circuit
What happens to potential difference/voltage in a series circuit?
it splits between components
What happens to resistance in a series circuit?
the total resistance is the sum of the resistance
What happens to current in a parallel circuit?
it splits between the branches
What happens to potential difference/voltage in a parallel circuit?
it stays the same throught the circuit
What happens to resistance in a parallel circuit?
the total resistance is smaller than the lowest resistance
RP - Investigate how changing the length of the wire affects its resistance: method
-set up a circuit with a cell, an ammeter, a voltmeter and a resistance wire
-Connect the crocodile clips to the resistance wire, 100 centimetres (cm) apart.
-Record the reading on the ammeter and on the voltmeter
-Move one of the crocodile clips closer until they are 90 cm apart.
-Record the new readings on the ammeter and the voltmeter.
-Repeat the previous steps reducing the length of the wire by 10 cm each time down to a minimum length of 10 cm.
-Use the results to calculate the resistance of each length of wire by using R = V/I, where R is resistance, V is voltage and I is current.
-Plot a graph of resistance against length for the resistance wire.
