-Umbra, total absence of light, total darkness, completely.
-Rays of light are completely blocked from the region or no light reaches this region
Wilfykil answered the question on March 27, 2019 at 13:00
- The strip placed n a pivot and kept in equilibrium by forces as shown in figure below(Solved)
The strip placed n a pivot and kept in equilibrium by forces as shown in figure below
(i) Determine the value of F and R
(ii) X is the distance from the end of the plank to the point of application of force F. Force F is now applied at various points nearer to the pivot so that x increases. Equilibrium is maintained all the time. On the axes provided sketch the relation between force F and x.
(iii) Give a reason for the answer in (ii) above
Date posted: March 27, 2019. Answers (1)
- A machine of velocity ratio 45, overcomes a load of 4.5 x 103N when an effort of 135N is applied.(Solved)
A machine of velocity ratio 45, overcomes a load of 4.5 x 103N when an effort of 135N is applied.
Determine:
(i) The mechanical advantage of the machine
(ii) Efficiency of the machine
(iii) The percentage of the work that goes to waste.
Date posted: March 27, 2019. Answers (1)
- Figure below shows part of a hydraulic press. The plunger is the position where effort is applied while the Ram piston is the position where...(Solved)
Figure below shows part of a hydraulic press. The plunger is the position where effort is applied while the Ram piston is the position where load is applied. The plunger has cross-section area, a m2 while the Ram piston has cross section area, a m2.
When the plunger moves down a distance d the Ram piston moves up a distance D.
(i) State the property of liquid pressure on which the working of the hydraulic press works.
(ii) Derive an impression for the velocity ratio (V.R) in terms of A and a.
Date posted: March 27, 2019. Answers (1)
- A sealed gas cylinder contains 300cm3 of certain gas at a temperature of 250C, and at a pressure of 9.5x 104pa. the gas in the...(Solved)
A sealed gas cylinder contains 300cm3 of certain gas at a temperature of 250C, and at a pressure of 9.5x 104pa. the gas in the cylinder was then cooled to 100C. Determine the new pressure of the gas in the cylinder.
Date posted: March 27, 2019. Answers (1)
- A block of metal of mass 150g at 1000C is dropped into a lagged calorimeter of heat capacity 40JK-1 containing 100g of water at 250C....(Solved)
A block of metal of mass 150g at 1000C is dropped into a lagged calorimeter of heat capacity 40JK-1 containing 100g of water at 250C. The temperature of the resulting mixture is 340C. (Specific heat capacity of water=4200JK-1).
Determine:
(i) Heat gained by calorimeter;
(ii) Heat gained by water;
(iii) Heat lost by the metal block;
(iv) Specific heat capacity of the metal block
Date posted: March 27, 2019. Answers (1)
- Figure below shows a toy resting on top of a closed bottle. Use the information on the figure to answer questions below(Solved)
Figure below shows a toy resting on top of a closed bottle. Use the information on the figure to answer questions below
a) Mark on the diagram, point Q, the approximate centre of gravity of the toy.
b) Giving a reason, name the state of equilibrium of the toy.
Date posted: March 27, 2019. Answers (1)
- Water is known to boil at 1000C. A student heated some water and noticed that it boiled at 1010C.
State two possible reasons for this observation(Solved)
Water is known to boil at 1000C. A student heated some water and noticed that it boiled at 1010C.
State two possible reasons for this observation
Date posted: March 27, 2019. Answers (1)
- Figure below shows a brick placed on a plane inclined at an angle ? to the horizontal. The weight, W, of the brick is shown.(Solved)
Figure below shows a brick placed on a plane inclined at an angle θ to the horizontal. The weight, W, of the brick is shown.
a) On the same diagram show with arrows the other two forces acting on the brick and name them.
b) State how each of the two forces named (a) above is affected when the angle θ is reduced.
Date posted: March 27, 2019. Answers (1)
- The masses of equal volumes of a certain liquid and of water were found to be mv and mw respectively. Given that the density of...(Solved)
The masses of equal volumes of a certain liquid and of water were found to be mv and mw respectively. Given that the density of water is 1gcm-3, express the density, p, of the liquid in terms of mv mw (show your work)
Date posted: March 27, 2019. Answers (1)
- The diagram below shows a rectifier circuit for an alternating current (a.c) input.(Solved)
The diagram below shows a rectifier circuit for an alternating current (a.c) input.
Draw the traces of the signal obtained on CRO connected across QS and PR.
Date posted: March 27, 2019. Answers (1)
- You are provided with a diode, a resisitor R, an a.c source of low voltage and connecting wires. In the space provided, sketch the circuit...(Solved)
You are provided with a diode, a resisitor R, an a.c source of low voltage and connecting wires. In the space provided, sketch the circuit diagram for a half-wave rectifier and indicate the terminals where the output voltage v0 may be connected.
Date posted: March 27, 2019. Answers (1)
- Using the components symbols shown in the fig, sketch a series circuit diagram for a forward biased diode.(Solved)
Using the components symbols shown in the fig, sketch a series circuit diagram for a forward biased diode.
Date posted: March 27, 2019. Answers (1)
- Sketch a current-voltage characteristic of a junction diode with a forward bias(Solved)
Sketch a current-voltage characteristic of a junction diode with a forward bias
Date posted: March 27, 2019. Answers (1)
- p- type and n-type semiconductors are made from a pure semiconductor by a process known as “doping”.
i) What is doping?
ii) Explain how the doping produces...(Solved)
p- type and n-type semiconductors are made from a pure semiconductor by a process known as “doping”.
i) What is doping?
ii) Explain how the doping produces an n-type semiconductor.
Date posted: March 27, 2019. Answers (1)
- A radio repairer wishes to use an ammeter to detect a faulty diode. With the aid of a circuit diagram describe how he will go...(Solved)
A radio repairer wishes to use an ammeter to detect a faulty diode. With the aid of a circuit diagram describe how he will go about this task.
Date posted: March 27, 2019. Answers (1)
- Name the quantities, which must be measured so as to determine the half-life of a radioactive sample whose half-life is known to be a few...(Solved)
Name the quantities, which must be measured so as to determine the half-life of a radioactive sample whose half-life is known to be a few hours.
Date posted: March 27, 2019. Answers (1)
- State two factors that determine the extent of the damage to the body cell caused by the radiation from radioactive substances.(Solved)
State two factors that determine the extent of the damage to the body cell caused by the radiation from radioactive substances.
Date posted: March 27, 2019. Answers (1)
- What is meant by the following terms:
Radioactive decay and isotope.(Solved)
What is meant by the following terms:
Radioactive decay and isotope.
Date posted: March 27, 2019. Answers (1)
- A monochromatic beam of radiation is directed on a clean metal surface so as to produce photo-electrons. Give a reason why some of the ejected...(Solved)
A monochromatic beam of radiation is directed on a clean metal surface so as to produce photo-electrons. Give a reason why some of the ejected photo-electrons have more kinetic energy than others.
Date posted: March 27, 2019. Answers (1)
- The diagram shows a photocell in action(Solved)
The diagram shows a photocell in action
i) The photocell is either evacuated or filled with an inert gas at low pressure. Give one reason for this
ii) What is the function of the resistor R in the circuit?
iii) State one reason for using a particular radiation such as ultraviolet for a given photocell.
iv) Explain how the set-up shown in the diagram may be used as an automatic switching device for a burglar alarm.
Date posted: March 27, 2019. Answers (1)