Basic Electronics Paper 2, WASSCE (PC 2ND), 2021

Question 2

       

State Ohm’s Law.
(b)        Figure 1 is a d.c. circuit diagram containing colour coded resistors R1 and R2.
     
Calculate the:

  1. maximum resistance of resistance R1;
  2. maximum resistance of resistance R2;
  3. maximum total resistance of the circuit;
  4. minimum current flowing through the circuit.

The expected responses were:

  1.              Ohm’s Law

    It states that the current flowing through a metallic conductor is directly proportional to the p.d. applied across its ends/terminals, provided the temperature remains constant.
    OR
    V = IR

    (b)
           

    (i)         R1 max = 100Ω  + 5Ω = 105 Ω
    (ii)        R2 max = 220 Ω + 11 Ω = 231 Ω
    (iii)       RT max = 105 Ω + 231 Ω = 336 Ω
    (iv)      



    The tasks in this question required candidates to specify resistance from colour codes and understand the concept of tolerance. The Chief Examiner reported that only a few candidates responded well to the tasks.