A 240v mains transformer has 800 turns in the primary and N turns in the secondary. It is used to supply energy to a 12v/21w lamp
(a) A 240v mains transformer has 800 turns in the primary and N turns in the secondary. It is used to supply energy to a 12v/21w lamp.
(i) Calculate the number of turns in the secondary (2mks)
(ii) What is the efficiency of the transformer if the current drawn from the 240V mains is 100mA (2mks)
(i) the reading of voltmeter, V, with, S, open (2mks)
(ii) the reading of the ammeter A with S closed (neglect the effective resistance of the secondary winding) (2mks)
(iii) the power dissipated in the lamp (2mks)
(iv) the primary current if the transformer is 90% efficient (3mks)
Complete the figure below to show how a single pulley can be arranged to a velocity ratio(V.R) of 2 (2mks)
K.C.S.E Physics Q & A - MODEL 2019PP1QN15
(a)Figure 6 shows n bottle top opener being used to open a bottle.
Indicate on the diagram the direction of the load and the effort.
(b) State two ways ¡n which an inclined plane can be made to reduce the applied effort when pulling a Load along the plane.
(c) A block and tackle system has three pulleys in the upper fixed block and two pulleys in the lower movable block.
(i) Draw a diagram to show how the system can be set up in order to lift a load arid indicate the position of the load and effort.
(ii) State the velocity ratio of the set up.
(iii) In such a block and tackle system an effort of 200N is required to lift a load of 600N. Determine its efficiency
K.C.S.E Physics Q & A - MODEL 2018PP1QN16
(a) An electric crane uses 8.0 x104 N of energy to lift a load of 2.0 X 104N in 4s.
FORM I - PHYSICS SYLLABUS
FORM II - PHYSICS SYLLABUS
FORM III - PHYSICS SYLLABUS
FORM IV - PHYSICS SYLLABUS
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