P4 - Electric Circuits - Complete Flashcards
What are the subatomic particles of the atom?
A proton, a neutron and an electron
What is a charged atom called?
An ion
What charge would an electron being removed result in in a otherwise neutral atom?
+1
Why do some insulators become charged when you rub them with another insulator?
As some of the electrons are charged from one material to the other
What charge would rubbing a polythene rod and a dry cloth together result in?
Negative
What charge would rubbing a perspex rod and a dry cloth together result in?
Positive
Like charges ……….. Unlike charges …………..
Repel, attract
The force between two charged objects is a ………………….. force
Non-contact
What is the function of a (chemical) cell?
To push electrons around a complete circuit. A battery is two or more cells put together
What is the function of a switch?
A switch enables the current in a circuit to be switched on or off
What is the function of an indicator?
An indicator, such as a bulb, is designed to emit light when current passes through it
What is the function of a diode?
It lets current pass in one direction only
What is the function of an ammeter?
An ammeter measures the current within a circuit
What is the function of a fixed resistor?
A fixed resistor limits the current in a circuit
What is the function of a variable resistor?
A variable resistor allows the current to be varied
What is the function of a fuse?
A fuse is designed to melt and therefore ‘break’ the circuit if the current is greater than a certain amount
What is the function of a heater?
A heater is used to transfer electric current into heat that can heat the surroundings
What is the function of a voltmeter?
A voltemeter is used to measure potential difference
What is an electric current?
The flow of charge
What is the size of an electric current also called?
The rate of flow of charge
What is electric charge measured in?
Coulombs (C)
What is electric current measured in?
Amperes (A)
What is 1 Amp equal to in Coulombs?
1 C per second
What is the equation that links charge flow and time taken?
Charge flow, C = Current, A x Time taken, t
What is potential difference?
The amount of work done on an electric component per coulomb of charge that passes through that component
How is a voltmeter connected to a circuit?
In parallel to the component it is measuring
What is the equation that links potential difference and energy transferred?
Potential difference across a component, V = Energy transferred, J / Charge, C
What causes resistance within a circuit?
Since the electrons have to push through many vibrating metal ions in the filament and wires - causing resistance
What is the equation that links resistance and current?
Resistance, Ohms (Omega symbol) = Potential difference, V / Current, A
What is Ohm’s law?
The current through a resistor at constant temperature is directly proportional to the potential difference across the resistor
What happens to the resistance of a filament lamp as its temperature increases?
Its resistance increases
What happens to a thermistor’s resistance as its temperature increases?
Its resistance decreases
What happens to a light dependent resistor’s resistance if light intensity increases?
Its resistance decreases
In a series circuit, ____________________ current passes through every component
In a series circuit, the same amount of current passes through every component
In a series circuit, the total potential difference of the power supply is _____________________ components
In a series circuit, the total potential difference of the power supply is shared between components
The total potential difference of cells in series is the sum of ____________________________
The total potential difference of cells in series is the sum of the potential difference of each cell
The total current in a parallel circuit is the sum of the ______________________________
The total current in a parallel circuit is the sum of the currents through the separate branches
In two parallel branches, how is this current split?
Equally - down the middle
For components in parallel, the potential difference across each component is ____________
For components in parallel, the potential difference across each component is the same
What is the equation that links current, voltage and potential difference?
Current (A) = Potential Difference (V) / Resistance (Ohms, Omega symbol)
What effect on the total resistance does adding more in parallel resistors have?
The total resistance goes down
