Equations

Question 1

Sensitivity =

Answer 1

Sensitivity = change in output / change in input

Question 2

Intensity I (Wm⁻²) =

Answer 2

Intensity I (Wm⁻²) = Power P (W) / Area A (m²)

Question 3

Curvature =

Answer 3

1/r

Question 4

Power =

Lenses

Answer 4

Power P (D) = 1/focal length f (m)

Question 5

1/v =

Answer 5

1/v = 1/u + 1/f

u is negative!!!

Question 6

Magnification m =

Answer 6

m = Image height / object height

= Image distance / Objet distance

Question 7

Total amount of info =

Answer 7

Info = No. of pixels * Bits per pixel

Question 8

Min rate of sampling >

Answer 8

Min rate of sampling > 2 * max. frequency of signal

Question 9

Rate if transmission of a digital information =

bits per second

Answer 9

bits per second = samples per second * bits per sample

Question 10

Power (W) =

Answer 10

P = W/t

Question 11

Resistance =

voltage

Answer 11

R = V/I

Question 12

Conductance =

voltage

Answer 12

G = I/V

Question 13

Energy per coulomb supplied by the source =

Answer 13

Energy per coulomb transferred in local resistance + energy per coulomb wasted in internal resistance

Question 14

E.m.f ϵ =

3 alternatives

Answer 14

ϵ = V + v
= I(R + r)
= V + Ir

V = terminal p.d  
v = lost volts 
R = resistance]
r = internal resistance
I = Current

Question 15

ϵₜₒₜₐₗ =

series

Answer 15

ϵₜₒₜₐₗ = ϵ₁ + ϵ₂ + ϵ₃…

Question 16

ϵₜₒₜₐₗ =

parallel

Answer 16

ϵₜₒₜₐₗ = ϵ₁ = ϵ₂ = ϵ₃ = …

Question 17

Total current entering a junction =

Answer 17

Total current leaving it

Question 18

total ϵ (series) =

voltage

Answer 18

ϵ = ΣIR

= ΣV

Question 19

Work done J =

force

Answer 19

= 1/2 Fx = Elastic strain energy