P2 - Current Electricity Flashcards
What is transferred when objects become charged?
Electrons.
What happens when two insulating materials are rubbed together?
Some materials become charged.
What happens when the charges are brought together?
Like charges repel; unlike charges attract.
What is a charged atom known as?
An ion
What affect does removing an electron from an atom have?
The atom becomes positively charged.
What is the purpose of a circuit diagram?
It shows how components are connected.
What is the difference between a battery and a cell?
A battery consists of two or more cells.
What determines the size of an electric current?
The rate of flow of charge.
How is electric current calculated?
Electric current = charge flow / time taken I = Q / t
What is potential difference?
Pd = energy transferred / charge V = W / Q
How is an ammeter connected to a circuit?
In series with the component giving the current through it.
How is a voltmeter connected to a circuit!
Parallel to the component giving the pd across it.
How is resistance calculated?
Resistance (ohms) = pd (volts) / current (amps)
What is the symbol for Ohms?
Ω
What is an ohmic conductor?
A component with a constant resistance.
What happens to the resistance of a filament bulb as the temperature increases?
The resistance increases with the temeprature. ∴ non-ohmic
How does the current through a diode depend on the pd across it?
For forward voltage, the resistance is low. For reverse voltage, the resistance is high. ∴ non-ohmic
How does the resistance of a thermistor change with temperature.
Resistance decreases when the temperature increases.
How does the current vary through a series circuit?
The same current passes through components in series.
How does the pd vary through a series circuit?
The total pd of the voltage supply in a series circuit is shared between components.
What happens to the pd when more than one cell is used in series?
The total pd is the sum of the pd of each cell.
How is the total resistance of a series circuit calculated?
Adding the resistance of each component.
How is the total current calculated in a parallel circuit?
The total current is the sum of the currents though the separate components.
What is the pd across the components in a parallel circuit?
The pd is the same across each component.
How is current through a resistor calculated?
current = pd / resistance
What is the relationship between resistance and current in a parallel circuit?
The bigger the resistance, the smaller the current.
What is the symbol for a cell on a circuit diagram?
What is the symbol for a resistor on a circuit diagram?
What is the symbol for a switch on a circuit diagram?
What is the symbol for a variable resistor on a circuit diagram?
What is the symbol for a bulb on a circuit diagram?
What is the symbol for a fuse on a circuit diagram?
What is the symbol for a diode on a circuit diagram?
What is the symbol for a heater on a circuit diagram?
What is the symbol for an LED on a circuit diagram?
What is the symbol for a voltmeter on a circuit diagram?
What is the symbol for an ammeter on a circuit diagram?
