Formulae for basic electrical and electronic principles
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Section 1
Formulae for basic electrical and electronic principles
General:
Magnetic Circuits:
Charge Q = I t Force F = ma
B=
Fm = NI A
S=
m.m.f. l = μ0 μr A
Work W = Fs Power P =
W t
Energy W = Pt
H=
NI l
B = μ0 μr H
Electromagnetism:
Ohm’s law V = IR or I = Conductance G =
1 R
Power P = V I = I 2 R =
V V or R = R I
Resistance R =
ρl a
V2 R
Resistance at θ ◦ C, Rθ = R0 (1 + α0 θ ) Terminal p.d. of source, V = E − I r
F = BI l sin θ
F = Qv B
Electromagnetic Induction: E = Blvsin θ E = − N
d dI = −L dt dt
W=
1 2 N N2 LI L = = 2 I S
M=
N1 N2 S
E2 = − M
Measurements: Series circuit R = R1 + R2 + R3 + · · · Parallel network
1 1 1 1 + + + ··· = R R1 R2 R3
Capacitors and Capacitance: V E= d
Q C= V
Q Q = It D = A
D ε0 εr A(n − 1) 1 = ε0 εr C = W = CV 2 E d 2 Capacitors in parallel C = C1 + C2 + C3 + · · · Capacitors in series
1 1 1 1 + + + ··· = C C1 C2 C3
Shunt Rs =
Ia r a V − I ra Multiplier RM = Is I
Power in decibels = 10 log
P2 P1
= 20 log
I2 I1
= 20 log
V2 V1
R2 R3 R1 l2 Potentiometer E 2 = E 1 l1 Wheatstone bridge RX =
These formulae are available for downloading at the website: www.routledge.com/cw/bird
d I1 dt
Section 1
Formulae for basic electrical and electronic principles
General:
Magnetic Circuits:
Charge Q = I t Force F = ma
B=
Fm = NI A
S=
m.m.f. l = μ0 μr A
Work W = Fs Power P =
W t
Energy W = Pt
H=
NI l
B = μ0 μr H
Electromagnetism:
Ohm’s law V = IR or I = Conductance G =
1 R
Power P = V I = I 2 R =
V V or R = R I
Resistance R =
ρl a
V2 R
Resistance at θ ◦ C, Rθ = R0 (1 + α0 θ ) Terminal p.d. of source, V = E − I r
F = BI l sin θ
F = Qv B
Electromagnetic Induction: E = Blvsin θ E = − N
d dI = −L dt dt
W=
1 2 N N2 LI L = = 2 I S
M=
N1 N2 S
E2 = − M
Measurements: Series circuit R = R1 + R2 + R3 + · · · Parallel network
1 1 1 1 + + + ··· = R R1 R2 R3
Capacitors and Capacitance: V E= d
Q C= V
Q Q = It D = A
D ε0 εr A(n − 1) 1 = ε0 εr C = W = CV 2 E d 2 Capacitors in parallel C = C1 + C2 + C3 + · · · Capacitors in series
1 1 1 1 + + + ··· = C C1 C2 C3
Shunt Rs =
Ia r a V − I ra Multiplier RM = Is I
Power in decibels = 10 log
P2 P1
= 20 log
I2 I1
= 20 log
V2 V1
R2 R3 R1 l2 Potentiometer E 2 = E 1 l1 Wheatstone bridge RX =
These formulae are available for downloading at the website: www.routledge.com/cw/bird
d I1 dt
