P4 Flashcards
cell
battery
lamp
ammeter
voltmeter fixed+ variable resistor light + light emitting diode fuse switcg
- converts stored chemical energy into electrical potential energy
- source of energy which provides a push
- bulb uses the electrical energy provided by the battery, but does not use current.
- instrument for measuring either direct or alternating electric current
- measures the difference in electrical potential between two points in an electric circuit.
- restrict current flow in a circuit - resistance that does not change , variable resistor is used in some dimmer switches and volume controls.
- a semiconductor diode which glows when a voltage is applied
- fuse breaks the circuit if a fault in an appliance causes too much current to flow
- switch serves the purpose of controlling the flow of electrical current
difference between a battery and a cell
A cell is a single unit device , A battery is either a primary battery or a secondary battery meaning it is rechargeable or non-chargeable.
what is current and how is it measured ?
measured in amperes - Current is a measure of how much electric charge flows through a circuit
why are metals good conductors of electricity
because the atoms in the metals form a matrix through which outer electrons can move freely
which way does current flow
Electrons flow from the negative terminal to the positive
what are the units for charge
coulomb (C)
what is the equation that links charge , flow , current and time
Energy transferred = power x time.
what is potential difference and how is it measured
Potential difference is measured using a device called a voltmeter
the difference of electrical potential between two points
what is resistance ? what unit are they
Resistance is a measure of the opposition to current flow in an electrical circuit , measured in ohms
explain how and why resistance changes in a long wire compared to a short wire
The resistance of a long wire is greater than the resistance of a short wire because electrons collide with more ions as they pass through.
explain how and why resistance changes in a thin wire compared to a thick wire
The resistance of a thin wire is greater than the resistance of a thick wire because a thin wire has fewer electrons to carry the current
resistance formula
resistance = voltage
————
current
what is ohms law
what is an ohms conductor
Ohm’s Law state that the voltage across a conductor is directly proportional to the current flowing through it,
an ohmic conductor
give the use of a light dependant resistor and thermistor
light-dependent resistors are used to detect light levels
Thermistors are used as temperature sensors
draw a series circuit
A series circuit is one loop; all electrons in that loop form one current. An ammeter will measure it
whats the rule for current in a series circuit
The amount of current is the same through any component in a series circuit.
give the rule for potential difference in a series circuit
The total potential difference supplied by the cell is divided up between the components.
give the rule for cells in a series circuit
The total resistance of a series circuit is equal to the sum of individual resistances
whats the equation for calculating total resistance in a series circuit
R1 + R2 + R3.
the rule for current in a parallel circuit
A parallel circuit has two or more paths for current to flow through. Voltage is the same across each component of the parallel circuit. The sum of the currents through each path is equal to the total current that flows from the source.
