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When the moon covers the sun it obstructs both light and heat since they move with the same velocity.
joseph rimiru answered the question on December 14, 2017 at 19:34
- An n-type semiconductor is obtained when germanium crystal is doped with arsenic. Explain how this change occurs. (N/B. Number of electrons in the outer...(Solved)
An n-type semiconductor is obtained when germanium crystal is doped with arsenic. Explain how this change occurs. (N/B. Number of electrons in the outer most shell for germanium = 4, and arsenic = 5
Date posted: December 14, 2017. Answers (1)
- What is meant by an extrinsic semiconductor?(Solved)
What is meant by an extrinsic semiconductor?
Date posted: December 14, 2017. Answers (1)
- Explain how doping produces an n-type semiconductor for a pure semiconductor material(Solved)
Explain how doping produces an n-type semiconductor for a pure semiconductor material.
Date posted: December 14, 2017. Answers (1)
- Explain why one feels colder when walking on a concrete floor than on a wooden carpet(Solved)
Explain why one feels colder when walking on a concrete floor than on a wooden carpet.
Date posted: December 13, 2017. Answers (1)
- A pure sample of silicon can be changed into p-type semi conductor by adding an impurity. Explain how this is achieved.(Solved)
A pure sample of silicon can be changed into p-type semi conductor by adding an impurity. Explain how this is achieved.
Date posted: December 12, 2017. Answers (1)
- Differentiate between a semiconductor and a conductor.
and give one example of each respectively.
(Solved)
Differentiate between a semiconductor and a conductor.
and give one example of each respectively.
Date posted: December 12, 2017. Answers (1)
- Describe how a p-type semiconductor is formed as explained in electronic study.(Solved)
Describe how a p-type semiconductor is formed as explained in electronic study.
Date posted: December 12, 2017. Answers (1)
- State three advantages of using GM tube instead of a diffusion cloud chamber to detect radiations from radiations from radioactive substance.(Solved)
State three advantages of using GM tube instead of a diffusion cloud chamber to detect radiations from radiations from radioactive substance.
Date posted: December 12, 2017. Answers (1)
- Explain why some of the tracks formed in a diffusion chamber are observed to be:
a. Short
b. Straight
(Solved)
Explain why some of the tracks formed in a diffusion chamber are observed to be:
a. Short
b. Straight
Date posted: December 12, 2017. Answers (1)
- Radiations from a radioactive source are detected using the Geiger Muller (GM) tube. State the function of:
i. The mica window
ii. Bromine gas in the tube
(Solved)
Radiations from a radioactive source are detected using the Geiger Muller (GM) tube. State the function of:
i. The mica window
ii. Bromine gas in the tube
Date posted: December 12, 2017. Answers (1)
- 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....(Solved)
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. Answers (1)
- 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...(Solved)
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. Answers (1)
- Short thick track were observed when a radiation was released into a diffusion cloud chamber. State with a reason the type of radiation was...(Solved)
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. Answers (1)
- 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...(Solved)
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. Answers (1)
- 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?(Solved)
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. Answers (1)
- A student carried out an experience to study the atoms of gold, a beam of a-particles was directed onto a thin sheet of gold. The...(Solved)
A student carried out an experience to study the atoms of gold, a beam of α-particles was directed onto a thin sheet of gold. The results were as follows:
i. Majority of the particles went through undeflected.
ii. A few particles deflected through varying angles up to 180⁰.
What inference can be made from these observations about the structure of the atom?
Date posted: December 11, 2017. Answers (1)
- 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.(Solved)
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. Answers (1)
- Give one reason why a- particles are more ionizing than ß-particles.(Solved)
Give one reason why α- particles are more ionizing than β-particles.
Date posted: December 11, 2017. Answers (1)
- 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...(Solved)
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. Answers (1)
- 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...(Solved)
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. Answers (1)