- Distinguish between intrinsic and extrinsic semi-conductors.(Solved)
Distinguish between intrinsic and extrinsic semi-conductors.
Date posted: March 25, 2019. Answers (1)
- A doctor suspects that one of the kidneys of a patient is not working properly. The doctor injects him with a radioactive impurity, 1MBq of...(Solved)
A doctor suspects that one of the kidneys of a patient is not working properly. The doctor injects him with a radioactive impurity, 1MBq of iodine-131 (half-life 8 days) which travels to his kidneys. A normal kidney gradually removes all impurity from the blood in about 20 minutes. The radioactivity in his kidney is monitored. using gamma ray detectors. The graph below shows the results.
a) Which kidney do you think is not working properly? Explain your answer.
b) Why do you think that a gamma ray emitter was used as the injected impurity instead of a beta emitter?
c) Why would it be less suitable to use as an impurity a material with a very short half-life?
Date posted: March 25, 2019. Answers (1)
- State the modification introduced in the modern buses so as to enhance stability(Solved)
State the modification introduced in the modern buses so as to enhance stability
Date posted: March 25, 2019. Answers (1)
- State the necessary conditions for equilibrium of body which is acted upon by a number of forces(Solved)
State the necessary conditions for equilibrium of body which is acted upon by a number of forces
Date posted: March 25, 2019. Answers (1)
- State two factors that determine the stability of a vehicle(Solved)
State two factors that determine the stability of a vehicle
Date posted: March 25, 2019. Answers (1)
- What the term background radiation mean?(Solved)
What the term background radiation mean?
Date posted: March 25, 2019. Answers (1)
- The figure shows zinc plate placed on the cap of a negatively charged electroscope. Ultraviolet radiation is made to fall on the plate.(Solved)
The figure shows zinc plate placed on the cap of a negatively charged electroscope. Ultraviolet radiation is made to fall on the plate.
i) What happens the leaf of electroscope.
ii) What would happen if the radiation was red light.
Date posted: March 25, 2019. Answers (1)
- Figure below shows a solid cylinder standing on a horizontal surface. The cylinder is in stable equilibrium.(Solved)
Figure below shows a solid cylinder standing on a horizontal surface. The cylinder is in stable equilibrium.
In the horizontal space provided, sketch the cylinders in neutral equilibrium
Date posted: March 25, 2019. Answers (1)
- Ultra violet radiation incident on zinc plate releases electrons from the zinc surface the energy of each incident photon is 5.4eV. Zinc has work fucntion...(Solved)
Ultra violet radiation incident on zinc plate releases electrons from the zinc surface the energy of each incident photon is 5.4eV. Zinc has work fucntion fo 4.3eV.State the name given to this effect.
Date posted: March 25, 2019. Answers (1)
- Why are people who are maimed or have lost one leg provided with crutches?(Solved)
Why are people who are maimed or have lost one leg provided with crutches?
Date posted: March 25, 2019. Answers (1)
- Give an expression which can be used to calculate electrical energy.(Solved)
Give an expression which can be used to calculate electrical energy.
Date posted: March 25, 2019. Answers (1)
- Why is it very difficult to open a door from a point too close to hinges?(Solved)
Why is it very difficult to open a door from a point too close to hinges?
Date posted: March 25, 2019. Answers (1)
- Why is a point source of X-rays needed to produce X-ray shadow photographs?(Solved)
Why is a point source of X-rays needed to produce X-ray shadow photographs?
Date posted: March 25, 2019. Answers (1)
- State the energy changes that occur in the cathode ray tube.(Solved)
State the energy changes that occur in the cathode ray tube.
Date posted: March 25, 2019. Answers (1)
- Sketch a diagram of a simple cell.(Solved)
Sketch a diagram of a simple cell.
Date posted: March 25, 2019. Answers (1)
- The figure shows a device for closing a steam outlet
Determine the weight W that just holds the bar in the horizontal position shown.(Solved)
The figure shows a device for closing a steam outlet
The area of the piston is 4.0 x 10-4 m2 and the pressure of the steam in the boiler
is 2.0 x 105Nm-2. Determine the weight W that just holds the bar in the horizontal
position shown.
Date posted: March 25, 2019. Answers (1)
- A battery rated 80Ah. What does this mean?(Solved)
A battery rated 80Ah. What does this mean?
Date posted: March 25, 2019. Answers (1)
- A power line from a power sub-station to a town a few kilometres away has a resistance of 0.1 Ohm per kilometre. Determine the rate...(Solved)
A power line from a power sub-station to a town a few kilometres away has a resistance of 0.1 Ohm per kilometre. Determine the rate of energy loss is transmission of power over 50km at a current of 60 amperes.
Date posted: March 25, 2019. Answers (1)
- The figure below shows an arrangement for lighting three lamps, A, B and C only one of which is controlled directly by the switch.(Solved)
The figure below shows an arrangement for lighting three lamps, A, B and C only one of which is controlled directly by the switch.
a) Which of he lamp is directly controlled by the switch?
b) What is the name given to this use of an electromagnet?
c) Which lamps can be on at once?
d) Explain how lamp C comes in.
Date posted: March 25, 2019. Answers (1)
- In an experiment, the diameter, of the patch was measured to be 200mm for an oil drop of radius 0.25mm. Determine the diameter of the...(Solved)
In an experiment, the diameter, of the patch was measured to be 200mm for an oil drop of radius 0.25mm. Determine the diameter of the molecule of the oil.
Date posted: March 25, 2019. Answers (1)