Electric power in a resistor can be written in different algebraic forms by relating potential difference V, current I and resistance R.
a. (i) State three distinct expressions for electrical power using these quantities only.
b. (ii) A student measures the current through a resistor and its resistance but does not know the potential difference across it. Which one of the expressions stated in part (i) should the student choose to calculate power? Give a reason for your answer.
c. (iii) For a consumer who is billed for electricity at a constant mains voltage, explain qualitatively why an appliance of lower resistance draws more power than one with higher resistance.