Basic Electronics Paper 2, WASSCE (SC), 2023

Question 1

 

    (a) (i) Define conductor.
    (ii) State three properties of a conductor.

    (b) An electric pressing iron takes 5 A when operated on a 220 V supply. Calculate the cost of operating the pressing iron for 12 hours at 20 kobo per kilowatt-hour (kWh).


                

 

 

  • The expected responses were:

  • (i) Definition of Conductor

 Conductors are materials which offer low resistance to the flow of current.
(ii)        Properties of a conductor                                           

  • High thermal conductivity
  • Low electrical resistance
  • Mechanically strong and flexible
  • High resistance to corrosion
  • Allows free movement of electrons or charges
  • Zero charge density in the conductor

(b)       Given that Current I = 5 A
V = 220 V
t = 12 hours
Power = IV                                      
= 5 × 220 = 1100 W = 1.1 kW          
Energy Consumed = Power × Time
= 1.1 kW × 12 hrs                 
= 13.2 kWh         
Cost of operation of 20 kobo per kWh
= 13.2 x 20
= 264 Kobo                            
= ₦ 2.64                                                                     

Many of those who attempted this question stated the definition and the three properties correctly and got the values required from calculation correctly. However, many did not put the unit.