- State the applications of radioactivity(Solved)
State the applications of radioactivity
Date posted: April 12, 2018.
- A radioactive substance has a half life of 10 hours. Calculate the percentage of the sample that remains after 25 hours.(Solved)
A radioactive substance has a half life of 10 hours. Calculate the percentage of the sample that remains after 25 hours.
Date posted: April 12, 2018.
- A radioactive substance is found to have an activity of 360 counts per second. 5minutes later, it was 45counts per second. Determine its half life.(Solved)
A radioactive substance is found to have an activity of 360 counts per second. 5 minutes later, it was 45 counts per second. Determine its half life.
Date posted: April 12, 2018.
- State the characteristics of gamma radiation(Solved)
State the characteristics of gamma radiation
Date posted: April 12, 2018.
- State the characteristics of beta radiation(Solved)
State the characteristics of beta radiation
Date posted: April 12, 2018.
- State the characteristics of alpha radiation(Solved)
State the characteristics of alpha radiation
Date posted: April 12, 2018.
- What are the applications of photoelectric effect?(Solved)
What are the applications of photoelectric effect?
Date posted: April 12, 2018.
- The threshold wavelength of a photoemissive surface is 0.45µm. calculate:
a. The threshold frequency of the surface.
b. The workfunction of the surface in eV.
c. The minimum...(Solved)
The threshold wavelength of a photoemissive surface is 0.45µm. calculate:
a. The threshold frequency of the surface.
b. The workfunction of the surface in eV.
c. The minimum speed with which a photoelectron is emitted if the frequency of the radiation is 7.5x1014Hz.
Date posted: April 12, 2018.
- Light of frequency 4.3x1014Hz is irradiated on a surface of metal whose workfunction is 2.6eV. Explain
whether photoelectric emission will occur or not(Solved)
Light of frequency 4.3x1014Hz is irradiated on a surface of metal whose workfunction is 2.6eV. Explain
whether photoelectric emission will occur or not
Date posted: April 12, 2018.
- Calculate the energy of a photon of light of frequency 5.0x1014Hz in (a) joules (b) electron-volt.(Solved)
Calculate the energy of a photon of light of frequency 5.0x1014Hz in (a) joules (b) electron-volt.
Date posted: April 12, 2018.
- State any differences between x-rays and cathode rays.(Solved)
State any differences between x-rays and cathode rays.
Date posted: April 12, 2018.
- An x-ray tube operates at 20kV. What is the shortest wavelength in its x-ray beam?
(Solved)
An x-ray tube operates at 20kV. What is the shortest wavelength in its x-ray beam?
Date posted: April 12, 2018.
- An x-ray tube operates at 10kV and a current of 15mA. Calculate the number of electrons hitting the target per second.(Solved)
An x-ray tube operates at 10kV and a current of 15mA. Calculate the number of electrons hitting the target per second.
Date posted: April 12, 2018.
- Explain how you can increase:
a) Quality of x-rays.
b) Intensity of the x-rays.
(Solved)
Explain how you can increase:
a) Quality of x-rays.
b) Intensity of the x-rays.
Date posted: April 12, 2018.
- Calculate the energy of x-rays whose frequency is 3x1016Hz.(Take h=6.63x10-9Js, e=1.6x10-19C, me=9.11x10-6kg and v=3.0x108m/s)(Solved)
Calculate the energy of x-rays whose frequency is 3x1016Hz.(Take h=6.63x10-9Js, e=1.6x10-19C, me=9.11x10-6kg and ?=3.0x108m/s)
Date posted: April 12, 2018.
- State the uses of X-Rays(Solved)
State the uses of X-Rays.
Date posted: April 12, 2018.
- Explain how X-Rays are produced(Solved)
Explain how X-Rays are produced
Date posted: April 12, 2018.
- State the uses of the Cathode Ray Oscilloscope (CRO)(Solved)
State the uses of the Cathode Ray Oscilloscope (CRO)
Date posted: April 12, 2018.
- State the components of a cathode ray oscilloscope (Solved)
State the components of a cathode ray oscilloscope
Date posted: April 12, 2018.
- An electric cooker has an oven rated 3 kW, a grill rated 2 kW and two rings each rated 500 W. The cooker operates from a 240V...(Solved)
An electric cooker has an oven rated 3 kW, a grill rated 2 kW and two rings each rated 500 W. The cooker
operates from a 24 0V mains. What is the cost of operating all the parts for 5 minutes if electricity costs Sh 1.50 per unit?
Date posted: April 11, 2018.
- A six bulb arrangement in a house runs for 8 hours every night for 5 days. If each bulb is rated 100 W and the cost of...(Solved)
A six bulb arrangement in a house runs for 8 hours every night for 5 days. If each bulb is rated 100 W and the cost of electrical energy is sh. 2.60 per unit, how much will the owner of the house pay at the end of the five days?
Date posted: April 11, 2018.
- An electric cooker has an oven rated 3kW, a grill rated 2kW and two rings each rated 500W. The cooker operates from 240V...(Solved)
An electric cooker has an oven rated 3kW, a grill rated 2kW and two rings each rated 500W. The cooker
operates from 240V mains. Would a 5A fuse be suitable for the cooker assuming that all the parts are switched
on?
Date posted: April 11, 2018.
- A power station produces 50kW at 240V. The power is transmitted through cables with a resistance of 0.4?. Calculate the percentage power loss during...(Solved)
A power station produces 50kW at 240V. The power is transmitted through cables with a resistance of
0.4?. Calculate the percentage power loss during transmission.
Date posted: April 11, 2018.
- Some length of a power line has a resistance of 10? and is transmitting 11kV and a current of 1A. If the
voltage is stepped...(Solved)
Some length of a power line has a resistance of 10Ω and is transmitting 11kV and a current of 1A. If the
voltage is stepped up to 160kV by a transformer, calculate:
a) The initial power loss
b) The power loss after step up
Date posted: April 11, 2018.
- State the main causes of energy losses in transformers:(Solved)
State the main causes of energy losses in transformers:
Date posted: April 11, 2018.
- A student designed a transformer to supply a current of 10A at a potential difference of 60V to an electric motor from an ac supply...(Solved)
A student designed a transformer to supply a current of 10A at a potential difference of 60V to an electric motor from an ac supply of 240V. if the efficiency of the transformer is 80%, calculate:
a) The power supplied to the transformer.
b) The current in the primary coil
Date posted: April 11, 2018.
- Calculate the number of turns of the secondary coil of a step down transformer which would enable a 12V bulb
to be used with a...(Solved)
Calculate the number of turns of the secondary coil of a step down transformer which would enable a 12V bulb
to be used with a 240V ac supply if there are 480 turns in the primary coil.
Date posted: April 11, 2018.
- State the applications of electromagnetic induction(Solved)
State the applications of electromagnetic induction
Date posted: April 11, 2018.
- Arrange the following radiations in order of increasing wavelength: infra red, blue light, UV light, radio
waves and X-rays.(Solved)
Arrange the following radiations in order of increasing wavelength: infra red, blue light, UV light, radio
waves and X-rays.
Date posted: April 11, 2018.
- An X-ray machine produces a radiation of wavelength 1.0x10-11m. calculate:
a) The frequency of the radiation.
b) The energy content of the radiation. (Solved)
An X-ray machine produces a radiation of wavelength 1.0x10-11m. calculate:
a) The frequency of the radiation.
b) The energy content of the radiation.
Date posted: April 11, 2018.