D.C. Circuits Flashcards
Single cell
Lamp
Battery of cells
Variable Resister
Thermister
Light dependent resister (LDR)
Ammeter
Voltmeter
Fuse
Switch
Diode
Series circuit
the current at every point in a series circuit is the_______________
same
the sum of the potential differences in a series circuit is equal to the ______________
potential difference across the whole circuit also called EMF
Current in parallel circuits
the current from the source is the sum of the currents in the separate branches of a parallel circuit.
6 A
Advantage of Parallel circuits
When two resistors are connected in series, the potential difference across the power source is ______________
shared between them
A _______________ is a single component that (in its simplest form) consists of a coil of wire with a sliding contact, midway along it
potentiometer
In the fiure below, what happens as the slider is moved upward?
f the slider in the above diagram is moved upwards, the resistance of the lower part will increase and so the potential difference across it will also increase
A relay consists of two parts
A coil (electromagnet)
A magnetic switch
A thermistor is a type of resistor (a thermal resistor) which changes its resistance when it is heated up:
As a thermistor gets hotter, its resistance _______
As it gets colder, its resistance __________
decreases, increases
An LDR (Light Dependent Resistor) is a type of resistor which changes its resistance when light is shone on it. How does resistance change as light intensity varies?
When more light is shone on an LDR its resistance decreases
If an LDR is covered up (reducing the light hitting it) its resistance increases.
Thermistors (or LDRs) may be used to create heat (or light) sensitive circuits, which perform certain actions when the temperature (or light) reaches a certain level
In the circuit below, an LDR is used, along with a relay, to control a bulb
When it gets darker, the resistance of the LDR increases
This causes the potential difference across the LDR to increase
When this potential difference increases the current in the coil (part of the relay) will increase
When the current gets large enough the coil will attract the switch, closing it and allowing a current to pass through the right-hand side of the circuit
A diode is a component which only allows charge to flow in ______________ direction through it
If a power source is connected back to front then there will be no current
one
Rectification
If a diode is connected to an a.c. (alternating current) power supply, it will only allow a current half of the time.
