Question

Electric current is the fundamental SI electrical dimension, with the ampere(A) as its unit. Determine units for the following quantities as combinations of fundamental SI units.

(a) Electrical Power

(b)Electrical Charge

(c)Electric Potential difference

(d) Electric resistance

(e) Electric capacitance

Answer 1

(a) units of electric power = watt (W) = J/s = N-m/s

= kg-m2/s3

(b) units of electric charge = coulomb (C) = Ampere-s

(c) units of Electric Potential difference = Volt (V)

= J/coulomb = N-m/A-s

= kg-m2/A-s3

(d) Electric resistance = ohm (Ω) = volt/A = W/A2

= kg-m2/s3-A2

(e) Electric capacitance = farad (F) = C/V

= (A-s)/(kg-m2/A-s3)

= s4-A2/kg-m2

Note

Name of units - notation

Watt - W

Joule - J

Second - s

Newton - N

Meter - m

Kilogram - kg

Ampere - A

Coulomb - C

Volt - V

ohm - Ω

farad - F