Radio,Television And Electronic Paper 2, WASSCE (SC), 2016

Question 2

(a) A resistor has a colour of red, green, orange and no band. Determine in ohms, its:

(a) A resistor has a colour of red, green, orange and no band. Determine in ohms, its:

  1. resistance;
  2. tolerance.

(b) Fig.2 a d.c. circuit.

Using the Kirchhoff’s Current Law, calculate:

  • (i) I2;
  • (ii) I4;
  • (iii) I5.

Observation

The expected answers were:


(a) Red – 2, Green – 5, Orange – 103, No band – 20% = (25 x 103)Ω ± 20%

  • (i) Resistance = 25 x 103 Ω = 25k Ω.                                                                                            
  • (ii) Tolerance = 20% x 25000 = ±5000 Ω.
  • (b) Using the Kirchhoff’s Current Law:
  • (i) I1 = I2 + I3

4 = I2 + 3
I2 = 1A.

  1. (ii) 2 = I4 + I6

1 + I4 = 2
I4 = 1A.

  1. (iii) 3 = I4 + I5

3 = 1 + I5
I5 = 2A.

 

  1. (c)Voltage drop across R5 =VR5 = I2R5.

Many candidates were unable to correctly apply the Kirchhoff’s Current Law.