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(50)/400 = (I)n n =3(half-lives)
(2)^n
Half –life 72 = 24 min.
Githiari answered the question on September 19, 2017 at 14:05
- The primary coils of a transformer has 2000 turns and carries a current of 3A. If the secondary coil
is designed to carry a current of...(Solved)
The primary coils of a transformer has 2000 turns and carries a current of 3A. If the secondary coil
is designed to carry a current of 30A, calculate the maximum number of turns in the secondary
coil.
Date posted: September 19, 2017. Answers (1)
- A heating coil rated 1000 W takes 15 minutes to heat 20kg of a liquid from 26^o C of 42^o C.
Determine the specific heat capacity...(Solved)
A heating coil rated 1000 W takes 15 minutes to heat 20kg of a liquid from 26^o C of 42^o C.
Determine the specific heat capacity of the liquid.
Date posted: September 19, 2017. Answers (1)
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(Solved)
Give one example of a semiconductor and one for a conductor
Date posted: September 19, 2017. Answers (1)
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Distinguish between semiconductor and conductors
Date posted: September 19, 2017. Answers (1)
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Which instrument which can be used to measure the thickness of the hair.
Date posted: September 19, 2017. Answers (1)
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State the accuracy of a vernier caliper.
Date posted: September 19, 2017. Answers (1)
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State the difference between conductors and insulators
Date posted: September 19, 2017. Answers (1)
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Explain why boiling water is not used to sterilize clinical thermometer.
Date posted: September 19, 2017. Answers (1)
- State any two reasons why water is not a suitable thermometric fluid.(Solved)
State any two reasons why water is not a suitable thermometric fluid.
Date posted: September 19, 2017. Answers (1)
- State why concrete is usually reinforced with steel in the construction of beams(Solved)
State why concrete is usually reinforced with steel in the construction of beams.
Date posted: September 19, 2017. Answers (1)
- Explain why trees bends towards a busy highway.(Solved)
Explain why trees bends towards a busy highway.
Date posted: September 19, 2017. Answers (1)
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Differentiate between pressure and force
Date posted: September 19, 2017. Answers (1)
- State any two special rays used in the construction of ray diagrams(Solved)
State any two special rays used in the construction of ray diagrams
Date posted: September 19, 2017. Answers (1)
- Electrons emitted from a metal when light of a certain frequency is shone on the metal are
found to have a maximum energy of 8.0 x...(Solved)
Electrons emitted from a metal when light of a certain frequency is shone on the metal are
found to have a maximum energy of 8.0 x 10-19J. If the work function of the metal is 3.2 x 10-19J,
determine the wavelength of the light used.
Date posted: September 19, 2017. Answers (1)
- A car can be brought to rest from a speed of 20 ms-1 in a time of 2s.
(i) Calculate the average deceleration
(ii) If the driver’s...(Solved)
A car can be brought to rest from a speed of 20 ms-1 in a time of 2s.
(i) Calculate the average deceleration
(ii) If the driver’s reaction time is 0.2s, determine the shortest stopping distance
Date posted: September 19, 2017. Answers (1)
- A drinking glass 0.02 kg contains 200gms of water at 20^0 C. A mass of 0.04 kg of ice at 0^0 C is
dropped into the...(Solved)
A drinking glass 0.02 kg contains 200gms of water at 20^0C. A mass of 0.04 kg of ice at 0^0 C is
dropped into the glass. Determine the final temperature of the mixture. Specific heat capacity of
glass = 670kg^-1K^-1. (Give your answer to correct one decimal place)
Date posted: September 19, 2017. Answers (1)
- State how eddy currents are reduced in a transformer(Solved)
How are eddy currents in the transformer minimized?
Date posted: September 19, 2017. Answers (1)
- State three factors that affect the speed of sound in the air(Solved)
State three factors that affect the speed of sound in the air
Date posted: September 19, 2017. Answers (1)
- Define the term wave(Solved)
Define the term wave
Date posted: September 19, 2017. Answers (1)
- The number of molecules in 18cm^3 of a liquid is 6 x 10^23. Assuming that the diameter of the
molecules is equivalent to the side of...(Solved)
The number of molecules in 18cm^3 of a liquid is 6 x 10^23. Assuming that the diameter of the
molecules is equivalent to the side of a cube having the same volume as the molecule. Determine
the diameter of the molecule.
Date posted: September 19, 2017. Answers (1)