04 - Electrical Circuits Flashcards
What do circuits allow us to do?
Manipulate voltages and currents so that we can do what we want (e.g. amplify, attenuate, filter, oscillate…)
Name 3 possible circuit components
Resistors Capacitors Inductors Battery (or other DC voltage source) AC Source (current or voltage) Ground Diode
In a series circuit, is the overall resistance the sum or product of the individual resistors?
Sum (R1 + R2 = Reff)
Which type of circuit is known as a “voltage divider”?
Series circuit
In a series circuit, what is the formula to find the current?
I = V/Reff
where Reff = the overall resistance
In a series circuit, what is the formula to find the voltage across R1?
R1 (kilo-ohms) x I (mA) = V (volts)
In a series circuit, the larger the resistance value, the _____ (lesser/greater) the voltage drop across it
Greater
If we know the voltage drops across the resistors of a series circuit, how do we find the voltage of the source?
Voltage of the source is equal to the sum of the voltage drop across the resistors
What type of circuit is known as a “current divider”?
Parallel circuit
True or False: Just like with water, in a parallel circuit more current flows through the path of least resistance
True
What is another name for a variable resistor?
A potentiometer
E.g. Volume dial on Walkman
Potentiometers are frequency-_______ (dependent/independent)
Independent
Electrical circuits containing only resistors will behave ______ (similarly/differently) for D.C. and A.C signals
Similarly
Electrical circuits containing resistors, capacitors, and inductors will behave ______ (similarly/differently) for D.C. and A.C signals
Differently - the electrical characteristics of capacitors and inductors are dependent on the frequency of the A.C. signal (a property which is exploited to design filters and oscillators)
With AC, low frequencies give capacitors time to store charge, so the capacitor acts as a(n) _______ (open/short) circuit
Open - flow of electricity will reduce as charge reaches capacitance
With AC, high frequencies don’t allow the capacitor time to store charge, so the capacitor acts as a(n) _______ (open/short) circuit
Short - constant flow of electrons back and forth make the capacitor appear as just a piece of conducting wire
In a series circuit with headphones, a capacitor acts as a simple ______ (low/high) pass filter, from the perspective of the headphones
High - the high frequencies change rapidly, so the capacitor doesn’t have time to charge, allowing the continued flow of current (low resistance), so there is increased current to, for example, the headphones.
-the low frequencies would allow the capacitor to charge, which would lead to decreased current, so the capacitor would act as an open circuit, blocking the current from reaching the headphones
Name one example of a passive element of a typical electrical circuit, and explain why
Resistors
Capacitors
Inductors
The most you can get is the input signal itself
Name one example of an active element in a typical electrical circuit and explain why
Amplifiers
They allow your output to be greater than your input signal
What are the 3 important classes of electronic circuits?
Attenuators - reduce the input voltage or current, and are typically made of resistive circuits
Filters - attenuate certain frequencies in the input signal
Amplifiers - increase the voltage, current, or power of the input signal while preserving its frequency characteristics. They employ active devices, such as transistors
When placed in a parallel circuit with headphones, a capacitor acts as a simple ____ (low/high) pass filter, from the perspective of the headphones
Low - Lower frequencies allow the capacitor to charge, which slows the flow of electrons (more resistance), so the current goes through the alternate pathway (e.g. headphones).
- the higher frequencies don’t allow the capacitor time to charge, so the pressure differential is maintained, and there is low resistance, so the capacitor would get most of the current (as opposed to the headphones).
