Get premium membership and access questions with answers, video lessons as well as revision papers.
50/400 =( ½)^n
Log 0.125 = n log 0.5
n= 3half lives
then half life = 72/3
=24 minutes
joseph rimiru answered the question on December 11, 2017 at 17:53
- 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)
- State the effect on the electrons emitted by the photoelectric effect when:
a. There is an increase of the intensity of the incident radiation
b. There is an...(Solved)
State the effect on the electrons emitted by the photoelectric effect when:
a. There is an increase of the intensity of the incident radiation
b. There is an increase of the frequency of the incident radiation
Date posted: December 10, 2017. Answers (1)
- What does the term work function mean?(Solved)
What does the term work function mean?
Date posted: December 10, 2017. Answers (1)
- A surface of metal whose work function is 6.4 x 10^-19 joules is illuminated with light of frequency 3.0 x 10^15 Hz. Find the maximum...(Solved)
A surface of metal whose work function is 6.4 x 10^-19 joules is illuminated with light of frequency 3.0 x 10^15 Hz. Find the maximum kinetic energy of the emitted photo electron. (use h = 6.51 x 10^-34)
Date posted: December 10, 2017. Answers (1)
- What is photoelectric effect?(Solved)
What is photoelectric effect?
Date posted: December 9, 2017. Answers (1)
- 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...(Solved)
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. Answers (1)
- 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...(Solved)
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. Answers (1)
- How many milligram in one kilogram?(Solved)
How many milligram in one kilogram?
Date posted: December 9, 2017. Answers (1)
- State the advantages of lead acid accumulator over primary cell(Solved)
Advantages of lead acid accumulator over primary cell
Date posted: December 9, 2017. Answers (1)
- Give the applications of reflection of sound (Solved)
Give the applications of reflection of sound.
Date posted: December 9, 2017. Answers (1)
- The surface of a metal was struck by a light of certain wavelength. State what determine the maximum kinetic energy of the electron emitted.(Solved)
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. Answers (1)
- 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)(Solved)
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. Answers (1)
- The electrons are accelerated by a p.d. of 24000v in a given X-rays tube. Assuming all the energy goes to produce X-rays, determine the frequency...(Solved)
The electrons are accelerated by a p.d. of 24000v in a given X-rays tube. Assuming all the energy goes to produce X-rays, determine the frequency of the X-rays produced. {Plank’s constant h= 6.62 x 10^-(34) Js and the charge on an electron e = 1.6 X10^(-19)C}
Date posted: December 7, 2017. Answers (1)
- State common systems of unit as used in environmental soil physics(Solved)
State common systems of unit as used in environmental soil physics.
Date posted: December 7, 2017. Answers (1)
- Define soil water potential(Solved)
Define soil water potential.
Date posted: December 7, 2017. Answers (1)
- 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...(Solved)
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. Answers (1)
- Define the term soil water potential as used in physics(Solved)
Define the term soil water potential as used in physics.
Date posted: December 6, 2017. Answers (1)
- 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.(Solved)
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. Answers (1)