P4 - Electric Circuits Flashcards
(21 cards)
What is needed for electrical charge to flow through a closed circuit?
- Circuit must include a source of potential difference
What is electrical current?
Rate of flow of charge
What does the current through a component depend on?
- Resistance of the component
- Potential difference across component
The greater the resistance of the component…
The smaller the current for a given potential difference(pd) across the component
What is the equation for charge flow?
Charge flow=current*time
What is the equation for potential difference?
Potential difference=current*resistance
How should ammeter be connected?
In series
How should a voltmeter be connected to determine potential difference?
In parallel
What does Ohm’s law say?
- Current through an ohmic conductor(at a constant temperature) is directly proportional to the potential difference across the resistor
- Resistance remains constant as current changes
What is the resistance of a filament lamp?
- Resistance of filament lamp increases as temperature of filament increases
What is the current in a diode like?
- Current flows in one direction only
- Diode has very high resistance in the reverse direction
As the thermistor increases in temperature..
the resistance decreases
As the LDR light intensity increases
The resistance decreases
Name an application of an LDR
Sensing circuits like lights turning on when it’s dark
Name an application of a thermistor
Thermostat
What happens to components connected in series?(3)
- Same current through each component
- Total potential difference of the power supply is shared between components
- Total resistance of two components is the sum of the resistance of each component
What happens to components connected in parallel?
- Potential difference across each component is the same
- Current through the whole circuit is the sum of the currents through the separate components
- Resistance of two resistors is less than the resistance of smallest individual resistor
When do certain insulating materials become electrically charged?
When they are rubbed against each other
What happens when two electrically charged objects are brought together?
They exert a force on each other
Where is the electric field the strongest?
Close to the charged object
What happens to the electric field when you are further away from the charged object?
The field becomes weaker
