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A house has five rooms each with a 60 W, 240 V bulb. If the bulbs are switched on from 7.00 pm to 10.30 pm,...
(Solved)
A house has five rooms each with a 60 W, 240 V bulb. If the bulbs are switched on from 7.00 pm to 10.30 pm, calculate the;
(a) Power consumed per day in kWh
(b) Cost per week for lighting those rooms if it costs 90 cents per unit.
Date posted:
October 16, 2018
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Answers (1)
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An electric kettle is rated at 2,500 W and uses a voltage of 240 V. (a) If electricity costs Ksh 1.10 per kWh, what is...
(Solved)
An electric kettle is rated at 2,500 W and uses a voltage of 240 V. (a) If electricity costs Ksh 1.10 per kWh, what is the cost of running it for 6 hrs? (b) What would be its rate of dissipating energy if the mains voltage was dropped to 120 V?
Date posted:
October 16, 2018
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Answers (1)
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Briefly explain the process of power generation and transmission
(Solved)
Explain the process of power transmission
Date posted:
October 16, 2018
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Answers (1)
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A step-up transformer has 10,000 turns in the secondary coil and 100 turns in the primary coil. An alternating current of 0.5 A flows in...
(Solved)
A step-up transformer has 10,000 turns in the secondary coil and 100 turns in the primary coil. An alternating current of 0.5 A flows in the primary circuit when connected to a 12.0 V a.c. supply.
(a) Calculate the voltage across the secondary coil (b) If the transformer has an efficiency of 90%, what is the current in the secondary coil?
Date posted:
October 16, 2018
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Answers (1)
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A current of 0.6 A is passed through a step up transformer with a primary coil of 200 turns and a current of 0.1 A...
(Solved)
A current of 0.6 A is passed through a step up transformer with a primary coil of 200 turns and a current of 0.1 A is obtained in the secondary coil. Determine the number of turns in the secondary coil and the voltage across if the primary coil is connected to a 240 V mains.
Date posted:
October 16, 2018
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Answers (1)
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A material of density 8.5 gcm-3 is attached to a piece of wood of mass 100g and density 0.2 gcm-3. Calculate the volume of material...
(Solved)
A material of density 8.5 gcm-3 is attached to a piece of wood of mass 100g and density 0.2 gcm-3. Calculate the volume of material X which must be attached to the piece of wood so that the two just submerge beneath a liquid of density 1.2 gcm-3.
Date posted:
October 16, 2018
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Answers (1)
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A balloon made up of a fabric weighing 80 N has a volume of 1.0 × 107 cm. the balloon is filled with hydrogen of...
(Solved)
A balloon made up of a fabric weighing 80 N has a volume of 1.0 × 107 cm. the balloon is filled with hydrogen of density 0.9 kgm-3. Calculate the greatest weight in addition to that of the hydrogen and the fabric, which the balloon can carry in air of average density 1.25 kgm-3
Date posted:
October 16, 2018
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Answers (1)
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A solid of mass 1.0 kg is suspended using a thread and then submerged in water. If the tension on the thread is 5.0 N,...
(Solved)
A solid of mass 1.0 kg is suspended using a thread and then submerged in water. If the tension on the thread is 5.0 N, determine the relative density of the solid.
Date posted:
October 16, 2018
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Answers (1)
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Describe experiment to determine the relative density of a cork
(Solved)
Describe experiment to determine the relative density of a cork
Date posted:
October 16, 2018
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Answers (1)
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A wooden block of dimensions 3 cm × 3 cm × 4 cm floats vertically in methylated spirit with 4 cm of its length in...
(Solved)
A wooden block of dimensions 3 cm × 3 cm × 4 cm floats vertically in methylated spirit with 4 cm of its length in the spirit. Calculate the weight of the block. (Density of methylated spirit = 8.0 × 102 kgm-3)
Date posted:
October 16, 2018
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Answers (1)
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Describe experiment to demonstrate the law of flotation
(Solved)
Describe experiment to demonstrate the law of flotation
Date posted:
October 16, 2018
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Answers (1)
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A block of metal of volume 60 cm3 weighs 4.80 N in air. Determine its weight when fully submerged in a liquid of density 1,200...
(Solved)
A block of metal of volume 60 cm3 weighs 4.80 N in air. Determine its weight when fully submerged in a liquid of density 1,200 kgm-3.
Date posted:
October 16, 2018
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Answers (1)
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Describe an experiment to demonstrate Archimedes principle
(Solved)
Describe an experiment to demonstrate Archimedes principle
Date posted:
October 16, 2018
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Answers (1)
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Explain the common eye defects and their corrections
(Solved)
Explain the common eye defects and their corrections.
Date posted:
October 15, 2018
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Answers (1)
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Experiment to determine the focal length of a converging lens using the lens formula
(Solved)
Experiment to determine the focal length of a converging lens using the lens formula
Date posted:
October 15, 2018
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Answers (1)
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The lens of a slide projector focuses on an image of height 1.5m on a screen placed 9.0 m from the projector. If the height...
(Solved)
The lens of a slide projector focuses on an image of height 1.5m on a screen placed 9.0 m from the projector. If the height of the picture on the slide was 6.5 cm, determine, (a) Distance from the slide (picture) to the lens (b) Focal length of the lens
Date posted:
October 15, 2018
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Answers (1)
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The focal length of a converging lens is found to be 10 cm. How far should the lens be placed from an illuminated object to...
(Solved)
The focal length of a converging lens is found to be 10 cm. How far should the lens be placed from an illuminated object to obtain an image which is magnified five times on the screen?
Date posted:
October 15, 2018
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Answers (1)
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An object 0.05 m high is placed 0.15 m in front of a convex lens of focal length 0.1 m. Find by construction, the position,...
(Solved)
An object 0.05 m high is placed 0.15 m in front of a convex lens of focal length 0.1 m. Find by construction, the position, nature and size of the image. What is the magnification?
Date posted:
October 15, 2018
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Answers (1)
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A girl claps her hands once at a distance 250 m from a vertical cliff. If the temperature in the surrounding is 5oC, how long...
(Solved)
A girl claps her hands once at a distance 250 m from a vertical cliff. If the temperature in the surrounding is 5oC, how long does it take for her to hear the echo?
Date posted:
October 12, 2018
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Answers (1)
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A boy strikes a railway line (steel) with a hammer. If the speed of sound in steel is 5,200 m/s, determine the time taken for...
(Solved)
A boy strikes a railway line (steel) with a hammer. If the speed of sound in steel is 5,200 m/s, determine the time taken for the sound to reach another boy 2.3 km down the railway line with his ear on the rail.
Date posted:
October 12, 2018
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Answers (1)