what is the role of an ammeter?
and where is it positioned in a circuit?
measures current in a circuit
in line with the component - as the current needs to flow THROUGH them
what is the role of a voltmeter?
and where is it positioned in a circuit?
measures the difference in voltage between two points
is positioned on both sides of a component - or on another ‘branch’
in a series circuit, describe the features of:
a) current
b) potential difference
c) resistance
a) current - is equal across all components
b) total pd is equal to addition of all pds
c) res - of all components is different
in a parallel circuit, describe the features of:
a) current
b) potential difference
c) resistance
a) current - split between different branches NOT EQUAL
b) pd across all components are equal
c) res - of all components are different
in a symbol of a cell, which one is positive and which is negative?
long one = positive
short one = negative
what two factors does current depend on?
resistance
potential difference
what is the equation to calculate potential difference?(give units and full words)
V = IR
potential difference (V) = current (A) x resistance (Ω)
define potential difference
the difference in voltage between two points
what is the difference between a variable resistor and a normal resistor?
a variable resistor’s resistance can change, a normal resistor’s resistance cannot
how does a battery cause a current to flow in a circuit?
in a cell, the positive terminal is at a higher electric potential than the negative terminal.
and so there is a POTENTIAL DIFFERENCE in which the electrons move from the higher energy terminal to the other (to balance out)
what is the equation to calculate the energy transferred in a circuit?
J = V x Q
energy transferred (J) = potential difference (V) x charge (C)
state the factor which allows the transfer energy in a circuit
resistance
explain how a hotter wire affects the resistance
- in wire/component, ions usually vibrate up and down
- vibrating ions get more energy so they vibrate faster
- so more electrons collide with the ions
SO MORE RESISTANCE AS MORE ENERGY IS TRANSFERRED BY CURRENT
