(i) It is a metal with a high melting point.
(ii) To slow down the rate as evaporation and increases the life of the filament.
joseph rimiru answered the question on January 6, 2018 at 19:51
- A hockey player trains on a nylon fiber surface. As he runs around, his shoes rub against the surface and he becomes positively charged.(Solved)
A hockey player trains on a nylon fiber surface. As he runs around, his shoes rub against the surface and he becomes positively charged.
(i) Explain in terms of particles involved, how he becomes positively charged.
Date posted: January 6, 2018. Answers (1)
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State the advantages of solid state devices over vacuum tubes.
Date posted: January 6, 2018. Answers (1)
- (a) What is diffusion? (b) A smoke cell contains a mixture of trapped air and smoke. The cell is brightly lit and viewed through a microscope. State...(Solved)
(a) What is diffusion?
(b) A smoke cell contains a mixture of trapped air and smoke. The cell is brightly lit and viewed through a microscope. State and explain what is observed.
(c) A beaker is filled completely with water. A spoon full of common salt is added slowly. The salt dissolves and the water does not overflow.
(i) Why is salt added slowly?
(ii) Why doesn't the water overflow?
Date posted: January 5, 2018. Answers (1)
- A stream of air passing over a roof of room at higher velocity than the velocity of air inside the room is likely to...(Solved)
A stream of air passing over a roof of room at higher velocity than the velocity of air inside the room is likely to blow off the roof. Give a reason for this
Date posted: January 5, 2018. Answers (1)
- Explain why in trying to move a rigid wall, a person is said to be doing no work at all.(Solved)
Explain why in trying to move a rigid wall, a person is said to be doing no work at all.
Date posted: January 3, 2018. Answers (1)
- What is the main difference between an a.c. and d.c generators?(Solved)
What is the main difference between an a.c. and d.c generators?
Date posted: January 3, 2018. Answers (1)
- Name two types of electromagnetic radiations whose wavelengths are greater than that of ultraviolet radiation (2 Marks) (Solved)
Name two types of electromagnetic radiations whose wavelengths are greater than that of ultraviolet radiation.
Date posted: January 3, 2018. Answers (1)
- Determine the cost of using an electric heater rated 3kW for 12 hours given that the cost of electricity per kilowatt-hour is Sh. 8.00.(Solved)
Determine the cost of using an electric heater rated 3kW for 12 hours given that the cost of electricity per kilowatt-hour is Sh. 8.00.
Date posted: January 3, 2018. Answers (1)
- State and explain the effect of increasing the extra high tension E.H.T in an x-ray tube on the x-rays. (Solved)
State and explain the effect of increasing the extra high tension E.H.T in an x-ray tube on the x-rays.
Date posted: January 3, 2018. Answers (1)
- A metal iron has work function of 6.8 x 10^-19J. Calculate the minimum frequency of light that can cause photoelectric emission. (Take h...(Solved)
A metal iron has work function of 6.8 x 10^-19J. Calculate the minimum frequency of light that can cause photoelectric emission. (Take h = 6.63 x 10^-34 Js)
Date posted: January 2, 2018. Answers (1)
- State the function of the control grid in a cathode ray oscilloscope(Solved)
State the function of the control grid in a cathode ray oscilloscope
Date posted: January 2, 2018. Answers (1)
- An electric bulb is rated ‘240V,100W .It contains a 1m long coiled tungsten wire . When switched on the wire reaches a temperature of...(Solved)
An electric bulb is rated ‘240V,100W .It contains a 1m long coiled tungsten wire . When switched on the wire reaches a temperature of about 2500 degrees Celsius.
(i) How much energy is given out by the bulb in 1second
(ii) Why is the wire coiled?
(iii) State two properties of tungsten which make it suitable for use in electric bulbs.
Date posted: January 2, 2018. Answers (1)
- There are two types of seismic waves produced by earthquakes. They are called P-waves and S-waves. P-waves are longitudinal and S-waves are transverse.(a) Explain...(Solved)
There are two types of seismic waves produced by earthquakes. They are called P-waves and S-waves. P-waves are longitudinal and S-waves are transverse.
(a) Explain what is meant by the terms longitudinal and transverse.
longitudinal
transverse
(b) State another example of a longitudinal wave, a transverse wave.
Date posted: January 2, 2018. Answers (1)
- A bar magnet AB is suspended freely so that it is able to rotate on a horizontal plane. It turns until end B points southwards....(Solved)
A bar magnet AB is suspended freely so that it is able to rotate on a horizontal plane. It turns until end B points southwards. Explain how the suspended magnet can be used to identify the north pole of another unmarked magnet.
Date posted: January 2, 2018. Answers (1)
- A certain wave of frequency 1000 Hz travels a distance of 600 m in 2 seconds. Determine the wavelength.(Solved)
A certain wave of frequency 1000 Hz travels a distance of 600 m in 2 seconds. Determine the wavelength.
Date posted: January 2, 2018. Answers (1)
- A glass rod is brought near the metal cap of a negatively charged electroscope. The observations are made; a metal rod is then brought...(Solved)
A glass rod is brought near the metal cap of a negatively charged electroscope. The observations are made; a metal rod is then brought near the metal cap of the same electroscope. State what is observed in the two cases.
Date posted: January 2, 2018. Answers (1)
- Give a reason why convex mirrors are preferred over plane mirror for use as rear view driving mirrors in cars ...(Solved)
Give a reason why convex mirrors are preferred over plane mirror for use as rear view driving mirrors in cars.
Date posted: January 2, 2018. Answers (1)
- State the effect on the image formed by a pin hole camera of increasing the size of the pinhole and keeping the distance between the...(Solved)
State the effect on the image formed by a pin hole camera of increasing the size of the pinhole and keeping the distance between the pinhole and object the same.
Date posted: January 2, 2018. Answers (1)
- (a) State the Archimedes principle (b) A light wooden block measuring 2cm by 5cm by 10cm floats in water with its length vertical(Solved)
(a) State the Archimedes principle (1mark)
(b).A light wooden block measuring 2cm by 5cm by 10cm floats in water with its length vertical. If ¾ of its length is submerged determine (density of water =1000kg/m^3)
(i) The density of the wooden block (3 marks)
(ii) The volume of the wooden block remaining above the surface when floating in a liquid of density 900kg/m^3. (3 marks)
(iii) Additional weight required to be placed on the wooden block so as to just submerge in this liquid
(3 marks)
(c) A meteorological weather balloon of volume 1.2m^3 is tied to a rigid support while being filled with helium gas. The mass of the fabric making the weather balloon is 0.3kg.Determine the maximum tension on the string tying the balloon to the rigid support.(density of air = 1.25kg/m^3 and density of helium is 0.18kg/m^3) (4 marks)
Date posted: January 1, 2018. Answers (1)
- Give a reason why a body moving around a vertical or horizontal circle accelerates yet its speed remains constant ...(Solved)
Give a reason why a body moving around a vertical or horizontal circle accelerates yet its speed remains constant.
Date posted: January 1, 2018. Answers (1)