revision Flashcards
(20 cards)
what is the equation for potential difference
potential difference = energy / charge
Defenition of resistance
the effort it takes for electrons to get through a component
what is the equation of resistance
resistance = potential difference / current
what is the equation for current
current = charge / time
what is the equation for power
power = energy / time
how does a thermistor affect resistance
when the heat of the thermistor rises, the resistance decreases
how does a light dependant resistor affect resistance
the resistance decreases when the light increases
what is a scalar
it is a quantity where we know the magnitude but not the direction e.g. heat, speed, time, volume
what is a vector
it is a quantity where we know the magnitude and the direction e.g. force, weight, velocity, distance
what are contact forces
air resistance, push, pull, upthrust, friction
what are non-contact forces
magnetic, gravitational, electrostatic
what is newton’s third law
when two objects interact they will exert equal and opposite forces on each other
what is mass
the amount of substance in an object. it is a scalar quantity measured in Kg
what is the equation for weight
weight = mass x gravitational field strength
what is resultant force
the combined effect of multiple forces acting on the same object
what is newton’s first law
an object at rest stays at rest and an object in motion stays in motion (with the same speed and direction) unless acted on by an unbalanced force
what is the equation for work done
work done = force x distance
what is the law about elastic forces
you must have at least 2 forces to stretch, compress or bend an object
what is the equation for force from elastics
force = spring constant x extension
what is another equation for power
power = current^2 x resistance
