sensing

Question 1

equation for total charge (Q)? (n, q)

Answer 1

Q = nq

total charge = no. of charge carriers x charge of 1 charge carrier

Question 2

equation for current (I)? (Q, t)

Answer 2

I = ΔQ/Δt

current = [change in] charge/[change in] time

can remember using “QuIt”:
ΔQ = IΔt

Question 3

equation for potential difference (V)? (E, Q)

Answer 3

potential difference = energy [transferred] [or work done]/charge

V = ΔE/ΔQ

Question 4

equation for resistance (R) of phonic resistor? (V,I)

Answer 4

R = V/I

Question 5

equation for conductance (G)? (R)

Answer 5

G = 1/R

Question 6

equation for conductance (G)? (V, I)

Answer 6

G = I/V

Question 7

equation for power (P)? (W or E, t)

Answer 7

P = W/t
or
P = E/t

where W = work done, or E = energy transferred

Question 8

equation for power (P)? (I, V)

Answer 8

P = IV

Question 9

equation for power (P)? (V, R)

Answer 9

P = (V^2)/R

Question 10

equation for power dissipation (P)? (I, R)

Answer 10

P = (I^2)R

Question 11

equation for power (P)? (F, v)

Answer 11

P = Fv

Question 12

equation for work done (W)/energy transferred (E)? (V, I, t)

Answer 12

W = VIt
or
E = VIt

Question 13

equation for current (I)? (P, V)

Answer 13

I = P/V

Question 14

equation for current (I)? (V, R)

Answer 14

I = V/R

Question 15

equation for resistance (R)? (V, P)

Answer 15

R = (V^2)/P

Question 16

equation for pd (V)? (P, I)

Answer 16

V = P/I

Question 17

equation for pd (V)? (R, P)

Answer 17

V = √(RP)

Question 18

equation for pd (V)? (I,R)

Answer 18

V = IR

Question 19

how does V behave in a series circuit?

Answer 19

V total = V1 + V2 + V3 + …

Question 20

how does I behave in a series circuit?

Answer 20

I total = I1 = I2 = I3 = …

Question 21

how does R behave in a series circuit?

Answer 21

R total = R1 + R2 + R3 + …

Question 22

how does G behave in a series circuit?

Answer 22

1/(G total) = 1/(G1) + 1/(G2) + 1/(G3) + …

Question 23

how does I behave in parallel circuit?

Answer 23

I total = I1 + I2 + I3 + …

Question 24

how does V behave in parallel circuit?

Answer 24

V total = V1 = V2 = V3 = …

Question 25

how does R behave in parallel circuit?

Answer 25

1/(R total) = 1/(R1) + 1/(R2) + 1/(R3) + …

Question 26

how does G behave in parallel circuit?

Answer 26

G total = G1 + G2 + G3 + …

Question 27

equation for resistivity (ρ)? (R, A, L)

Answer 27

ρ = RA/L
or
RA = Lρ
“ralp”

Question 28

equation for conductivity (σ)? (G, L, A)

Answer 28

σ = GL/A
or
GL = Aσ
“glass” (bc sigma makes an “s” noise)

Question 29

equation for resistivity (ρ)? (σ)

Answer 29

ρ = 1/σ

Question 30

equation for emf (ε)? (I, r, V)

Answer 30

ε = V + Ir
or
V = ε - Ir

where ε = emf and r = internal resistance

Question 31

equation for emf (ε)? (I, R, r)

Answer 31

ε = I(R + r)

Question 32

equation for emf (ε)? (V, v lost)

Answer 32

ε = V + v lost
or
V = ε - v lost

where V = terminal pd and v lost = energy lost/work done in overcoming internal resistance

Question 33

equation for V out in potential divider circuit? (R1, R2, V in)

Answer 33

V out = V in x [R2/(R1 + R2)]

Question 34

ratio of Vs to Rs in potential divider circuit? (V1, V2, R1, R2)

Answer 34

V1:V2 = R1:R2

Question 35

equation for sensitivity [of sensor]?

Answer 35

sensitivity = change in output/change in input
or
sensitivity = Δreading on instrument/Δexternal condition
or
sensitivity = meter resolution/Δexternal condition

where external condition = eg, temp

Question 36

equation for sensitivity for thermometer/heat sensor circuit? (R min, T min)

Answer 36

sensitivity = ΔR min/ΔT min
or
sensitivity = meter resolution/ΔT min

where R min = min value of ΔR and ΔT = value of ΔT for ΔR min