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.
answers
K.C.S.E Physics Q & A - MODEL 2004PP1QN21&22
​A certain powder of mass. 0.10kg was heated in a container by an electric heater rated 50 w for sometime. The graph below shows the variation of the temperature of the powder with time. Use this information and the graph to answer question
21 and 22. 
i) Determine the quantity of heat by the heater from the time the power starts to melt to the time it has all melted.
ii) Determine the specific latent heat of fusion of powder assuming the container absorbs negligible amount of heat
answers
K.C.S.E Physics Q & A - MODEL 2004PP1QN20
​ An electric heater is connected to the mains supply. A fault in the mains reduces the supply potential slightly.
Explain the effect on the rate of heating of the heater.
answer
K.C.S.E Physics Q & A - MODEL 2002PP1QN30
The following table shows electrical appliances to be used in a house. The electrical rating for each appliance is shown. The following fuses are available, 5A, 15A, 30A and 45A.
​Determine which one of the fuses is suitable for the house.
answer
K.C.S.E Physics Q & A - MODEL 2002PP1QN18
An electric bulb with a filament of resistance 480ohms is connected to a 240V mains supply.
Determine the energy dissipated in 2 minutes
answer
K.C.S.E Physics Q & A - MODEL 1999PP1QN34
Figure 17 shows the electric wiring of an electric heater A, B, C are the main wires.
Identify A ,B, and C.
ANSWERS
K.C.S.E Physics Q & A - MODEL 1997PP1QN18
A transformer in a welding machine supplies 6 volts from a 240V main supply. If the current used in the welding is 30A. Determine the current in at the mains.
ANSWERS
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