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Explain why some of the tracks formed in a diffusion chamber are observed to be:
a. Short
b. Straight
Date posted:
December 12, 2017
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The half life of a radioactive substance is 12 years. Determine the time it would take to decay to 12.5% of it original value.
Date posted:
December 12, 2017
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An element x has a half life of 3.83 days. If a sample of this element is found to disintegration per second at a particular time. Determine its activity rate after 19.15 days.
Date posted:
December 12, 2017
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Short thick track were observed when a radiation was released into a diffusion cloud chamber. State with a reason the type of radiation was detected.
Date posted:
December 12, 2017
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A certain sample of radioactive material has a half life of 130 days and has 1.0 x 10^20 atoms initially. Determine the number of radioactive atoms that have decayed after 390 days.
Date posted:
December 11, 2017
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A radioactive Cobalt 60 has a half life of 5.25 years. What fraction of the original atoms in a sample will remain after 21 years?
Date posted:
December 11, 2017
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A radioactive substance activity, initially at 400 counts per seconds reduces to 50 counts per second in 72 minutes. Determine the half-life of the substances.
Date posted:
December 11, 2017
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Give one reason why α- particles are more ionizing than β-particles.
Date posted:
December 11, 2017
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A radiation of wavelength 4.3 x 10^-7 m is shone on two different metal surface, nickel and potassium . (Speed of light 3.0 x10^8m/s, plank’s constant h as 6.63 x 10^-34 Js
i. Determine the energy of the incident radiation.
ii. If the work function of nickel is 8.0 x 10^-19J and that of potassium 3.68 x 10^-19J, which of the two metal will the given light eject electrons, state the reason.
iii. Calculate the velocity of the emitted electrons from the metal surface in (ii) above. (take the mass of an electron as 9.1 x 10^-31kg)
Date posted:
December 10, 2017
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The maximum wavelength required to make possible photoelectric emission on a metal surface is irradiated with light f frequency 8.5 x 10^14 Hz.
Determine:
i. The threshold frequency.
ii. The work function of the metal in electron volts.
iii. The maximum kinetic energy f the electron.
Given that 1 eV = 1.6 x 10^-19J
Speed of light =3.0 x 10^8m/s
Plank’s constant h = 6.63 x 10^-34 Js
Date posted:
December 10, 2017
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What does the term work function mean?
Date posted:
December 10, 2017
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The work function of a certain material is 3.5 eV. Determine the threshold frequency for the material. (1 electron volt eV = 1.6 x 10^-19 J, and plank’s constant h = 6.62 x10^-34 Js )
Date posted:
December 9, 2017
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The minimum frequency of radiation needed to cause photoelectric effect on a certain metal surface is 9.05 x 10^14 Hz. Determine the work function of the metal. (Plank’s constant h=6.63 x 10^-34 Js).
Date posted:
December 9, 2017
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How many milligram in one kilogram?
Date posted:
December 9, 2017
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Advantages of lead acid accumulator over primary cell
Date posted:
December 9, 2017
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Give the applications of reflection of sound.
Date posted:
December 9, 2017
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The surface of a metal was struck by a light of certain wavelength. State what determine the maximum kinetic energy of the electron emitted.
Date posted:
December 7, 2017
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Calculate the photon energy in ultra violet radiation whose frequency is 8.70 x 10^14 Hz. (Plank’s constant, h = 6.63 x 10^-34Js)
Date posted:
December 7, 2017
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State common systems of unit as used in environmental soil physics.
Date posted:
December 7, 2017
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Define soil water potential.
Date posted:
December 7, 2017
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A stone is thrown in water at a distance of 6 m from a bank and produces 12 crests of waves which took 10 minutes to reach the bank.
Find the frequency of the wave.
Date posted:
December 6, 2017
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Define the term soil water potential as used in physics.
Date posted:
December 6, 2017
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The X-rays are used for detecting cracks inside metal beams.
i. State the type of the x-rays used.
ii. Give a reason for the above answer.
Date posted:
December 5, 2017
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If one increases the E.H.T. in the X-ray tube, state and explain what will happen to the X-rays produced.
Date posted:
December 5, 2017
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How do you convert binary number to BCD.
Date posted:
December 5, 2017
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How do you convert Binary Coded Decimal(BCD) to binary.
Date posted:
December 5, 2017
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Alternating current (a.c.) is used for transmitting electricity over long distance, state the reason.
Date posted:
December 4, 2017
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9. The follow table shows electric appliances to be used in a home. The electrical rating for each appliance is shown. The fuses available are 5A, 15A, 30A and 45 A
Appliance-----voltage(V)-----Power(w)
T.V.----------240----------300
Iron box------240----------720
Electrical kettle--240----2400
Determine which one of the fuses is suitable for the house.
Date posted:
December 4, 2017
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Heating in the coils when current flows is one of the causes of energy loss in a transformer. State :
(i) The reason why the current causes heating.
(ii)How the heating can be minimized.
Date posted:
December 4, 2017
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The primary coil of a transformer has 2000 turns and secondary coil is connect to a 240V a.c. mains supply.
(a)Explain how an e.m.f. is induced in the secondary voltage.
(b)Determine the secondary voltage
Date posted:
December 4, 2017