Electrical And Digital Fundamentals Flashcards
Series cct:
Current
Voltage
Resistance
It = I1 = I2 ect
Vt = V1 +V2 ect
Rt = R1 + R2 ect
Parallel cct:
Voltage
Current
Resistance
Vt = V1 = V2 ect
It = I1 + I2 (kirchoffs current )
Rt = 1/ (1/R1 + 1/R2 ect)
Power formulas
P = I x V
P = I^2 × R
P = V^2 / R
T = 1/f is for
Time 1 cycle takes
T in sec
f frequency in Hz
V = Vp × sin X is for
Instantaneous Voltage
Vp = Vpeak
X is degrees of sin wave
Vp x .707 gives
Rms / effective value of sin wave
How much power is lost when a load of 20a is carried by a conductor with an Rt of .033
P = I^2 × R
P = 400 × .033
P = 13.2
How much resistance for a 20 watt resistor hooked upto 24 v?
This is for
Capacitors in ac series cct
This is for
Capacitors in series ac cct
Micro farads
t = RC is for
Time constant with capacitor dc cct
Time constant?
This is for?
Unit of measurement (answer)?
Capacitive reactance
Ohms
Each letter stands for?
This is for?
Capacitive reactance in series
This is for
Impedance in a cct with a capacitor
If you have .a .68 a 60hz supply what is the Vdrop across a 47uf capacitor?
CIV is my acronym for
Capacitive cct current leads voltage
This is for
Capacitors in parallel
This is for
Capacitive reactance in parallel
This is for
Total inductance in series ac
This is for?
1 inductive time constant in DC cct
This is for ?
F and L stand fot
Inductive reactance
F = frequency
L= in henries
This is for
Inductors in parallel
This is for?
Inductive reactance in parallel
Why are inductors sometimes called choke coils
They suppress sudden rise / fall in current
A conductor has how many valence electrons
1 to 3
A semi conductor has how many valence electrons
4
An insulator has how many valence electrons?
5 to 8
What can happen if you open a cct with a choke? Why is it important to suppress it?
A huge cemf spike
Because it can damage electonics
When you put voltage into P TYPE semi conductor material: ( electrons do what?)
It fills up the holes in molecular lattice and move up the conductor like bubbles at the bottom of a water cooler
A diode is made by? Does?
Attaching wies to a PN junction
Allows current to flow in 1 direction only
This is a?
Letters stand for?
A diode
A = annode
K = cathode
Def diode barrier potential
A certain minimum amount of voltage must be pushed across the PN junction so current can start to flow
This is a
Reverse bias diode
This is a
Zener diode
ELI the ICE man is
Voltage leads current inductive
Current leads voltage capacitive
A forward biased diode only allows current to flow if
The anode is positive with respect to the cathode
Most common element in semi conductor / solid state devices
Silicon (Si)
What is the rectified dc voltage for 3a 120v 60hz supply. Its ripple frequency?
V(ad) = 120/2 =60v
V(peak) = 60/.707 = 84.9
V(cd) = 84.9 × .637 = 54 vdc
RIPPLE:
2× f(hz) = 2 × 60 = 120
What is the % ripple of a 240 Vdc with an rms of 24v?
% = (rms/dc average )× 100
% = (24/240) × 100
% = .1 × 100 = 10%
What thermocouple provides the most linear response to a change in temp?
Type k
Seebeck calc for overall sensitivity
= 41.5 uV/ ‘C
Seebeck calc
Tm = Tr + V/S
Tr = 0’c
V = .00358
S = .0000415
Tm = 85’c
If using tables what # would you have?
Eo = Em-Er
Em = 4.279 - .790
You would look up 3.489 on type k table (about 85 -86 on type k)
A voltage of 3.217 mV is measured across a K type thermocouple. The reference junction is at 22’c. What is the measured temp of the thermocouple?
Eo = Em- Er so:
Em = Eo + Er
Em = 3.217 + .879
Em = 4.096 = 100’c