Work Package 2 Flashcards
what are capacitors used for?
used in electrical circuits to store an electrical charge
what two things are printed on a capacitor?
- capacitance value
2. working voltage
what five things do capacitors do?
- create time delays (monostable)
- control the frequency of pulse generators (astable)
- smooth the input across a power supply
- used to store electrical charge - ‘super’ capacitors replace batteries
- allow alternating current (AC) flow, block direct current flow
how can a capacitor be instantly charged?
by connecting a power supply across its two leads
the rate at which the capacitor charges depends on two things, what are they?
- the size of capacitor
2. the current limiting resistor
what is the formula for time constant? (given)
capacitor time constant (seconds) = capacitance (farads) X resistance (Ohms)
what is a way of controlling the rate of which a capacitor charges?
- by connecting a current limiting resistor in series with the capacitor
how does a capacitor discharge?
the same way it charges
are electrolytic capacitors made with a large or small capacitance value and what is the tolerance to?
with a large capacitance value to a tolerance of plus/minus 20%
what is the tolerance level of a non-electrolytic capacitor?
plus/ minus 1%
when there is a capacitor in series, is the total capacitance smaller or larger than the smallest individual capacitance?
its always smaller than the smallest individual capacitance
what is the formula for the total capacitance in a series circuit?
1/ Ctotal = 1/C1 + 1/C2
what is the formula for the total capacitance in a parallel circuit?
Ctotal = C1 + C2
what are three types of capacitors?
- ceramic capacitors
- electrolytic capacitors
- variable capacitors
on a capacitor, does the shorter leg go to the positive or negative side?
goes to the negative side
