K.C.S.E Physics Q & A - MODEL 2019PP2QN11
​Figure 5 shows part of the lighting circuit in a house.
​State two errors in the wiring circuit.
answers
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K.C.S.E Physics Q & A - MODEL 2018PP2QN15
​(a) Electrical energy is transmitted at very high voltages and low current
(i) Describe how the high voltages are attained (ii) State two reasons why thick aluminum wires are preferred to Copper Wires for transmission Over long distances (b) Figure 4 shows an electric cooker connected to the mains supply, X,Y and Z are the mains wires 
​State with a reason the name of wire Y.
(c) A student has some coloured bulbs rated 60 W, 240 V to be connected for decorations. (i) State the number of such bulbs that can be connected normally to a 240V supply through a 5A fuse. (ii) If the cost of electric energy is Ksh 3.00 per kWh, determine the cost of running the bulbs in (c) (i) for 5 hours daily for 20 days.
answers
(a)(i) By use of step-up transformers low input voltages are stepped up to high voltages for transmission.
(ii) They are cheaper They are lighter, lower density / lower weight b) Y is the earth wire, it is connected to the casing of the cooker 
K.C.S.E Physics Q & A - MODEL 2018PP2QN06
An electric kettle is rated 1.8kW, 240 V. Determine the rating of the fuse that may be used in the kettle.
answer
K.C.S.E Physics Q & A - MODEL 2015PP2QN15
​.(a) State two factors that determine the resistance of a metallic conductor.
(b) Explain how a fuse safeguards electrical appliances against excessive currents.
​(c) A hair dryer is rated 2.5 kW, 240 V.
(i) Determine whether a 10 A fuse may be suitable for the hair dryer. (ii) Determine the cost of using the hair dryer for 3 hours if the cost of electricity is Ksh 0.80 per kilowatt hour.
answer
​(a) length of conductor
area of cross-section temperature resistivity of conductor (b) When excessive currents flow through the circuit, the wire gets heated and melts hence breaking the circuit. 
​Fuse not suitable since current through the appliance is higher than the fuse rating
K.C.S.E Physics Q & A - MODEL 2006PP2QN21
​(a) Figure 12 shows a section of a house wiring system
(i) Name:
The circuit labeled P The terminals labeled X and Y X Y II Give a reason why R is connected to Y but not to X (ii) Why is the earthing necessary in such a circuit? (b) Determine the cost of using an electric iron rated 1500W, for a total of 30 hours given that the cost of electricity per kWh is Kshs 8.
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