10.3 Analysing circuits

Question 1

Kirchhoff’s laws

Answer 1

ΣIin=ΣIout
Σε=ΣV

Question 2

Resistors in series/parallel

Answer 2

Series
RT=R1+R2+…+Rx
where x is the number of total number of resistors

Parallel
1/RT = (1/R1)+(1/R2)+…+(1/Rx)
1/RT=x/y
RT=y/x

Question 3

Internal resistance

Answer 3

ε=Ir+v
ε=I(r+R)
r=(ε-V)/I
V=ε-Ir
R=(ε-Ir)/I

Question 4

p.d. / e.m.f.

Answer 4

V=IR
ε=W/Q

Question 5

Ohm’s law

Answer 5

R=V/I
ohmic conductor : linear
non-ohmic : non-linear

Question 6

Electrical power

Answer 6

W=Pt
P=W/t

Question 7

What are the 4 key electrical relationships?

Answer 7

I=ΔQ/Δt
V=W/Q
P=VI
V=IR