Soft iron armature should be easily magnetized and demagnetized. It concentrates the matnetic field inside the core to increase the magnetic strength.
Kavungya answered the question on May 31, 2019 at 07:57
- A boy observes his face in a concave mirror of focal length 100cm. If the mirror is 80cm away, state one characteristic of the image...(Solved)
A boy observes his face in a concave mirror of focal length 100cm. If the mirror is 80cm away, state one characteristic of the image observed.
Date posted: May 31, 2019. Answers (1)
- The figure below shows the image behind a mirror M.
By ray diagram construction, locate the position of the object.(Solved)
The figure below shows the image behind a mirror M.
By ray diagram construction, locate the position of the object.
Date posted: May 31, 2019. Answers (1)
- Explain why a body moving in horizontal circular motion does no work.(Solved)
Explain why a body moving in horizontal circular motion does no work.
Date posted: May 31, 2019. Answers (1)
- A transformer has 800 turn in the primary and 40 turns in the secondary winding. The alternating
e.m.f connected to the primary is 240v and the...(Solved)
A transformer has 800 turn in the primary and 40 turns in the secondary winding. The alternating
e.m.f connected to the primary is 240v and the current is 0.5A.
Determine
i) The secondary e.m.f
ii) The power in the secondary if the transformer is 95% efficient.
Date posted: May 31, 2019. Answers (1)
- A bar magnet is moved into a coil of insulated copper wire connected to a centre-zero galvanometer as shown in figure below.
i) Show on the...(Solved)
A bar magnet is moved into a coil of insulated copper wire connected to a centre-zero galvanometer as shown in figure below.
i) Show on the diagram the direction of induced current in the coil.
ii) State and explain clearly what is observed on the galvanometer when the magnet is moved into and then withdrawn from the coil.
Date posted: May 31, 2019. Answers (1)
- A pendulum bob is raised to a height of 60cm above its lowest point and made to swing as shown in the figure.
Determine the velocity...(Solved)
A pendulum bob is raised to a height of 60cm above its lowest point and made to swing as shown in the figure.
Determine the velocity of the mass at the height where kinetic energy is equal to the potential energy.
Date posted: May 31, 2019. Answers (1)
- Figure below shows two rays of monochromatic light incident on two adjacent slits S1 and S2
State what is observed on the screen when the:
i) Distance...(Solved)
Figure below shows two rays of monochromatic light incident on two adjacent slits S1 and S2
State what is observed on the screen when the:
i) Distance X is increased.
ii) Slit separation, d is reduced.
iii) White light is used.
Date posted: May 31, 2019. Answers (1)
- The wave shown in figure below has a velocity of 200m/s
Determine
i) The period T of the wave
ii) The frequency of the wave.
iii)...(Solved)
The wave shown in figure below has a velocity of 200m/s
Determine
i) The period T of the wave
ii) The frequency of the wave.
iii) The wavelength of the wave.
Date posted: May 31, 2019. Answers (1)
- The figure below shows a pulley system being used to raise a load.
Given that the size of the load is 500N and the effort applied...(Solved)
The figure below shows a pulley system being used to raise a load.
Given that the size of the load is 500N and the effort applied is 200N, calculate the efficiency of the machine.
Date posted: May 31, 2019. Answers (1)
- Figure below shows an isolated positive point charge P
On the figure, sketch the electric field pattern around the charge.(Solved)
Figure below shows an isolated positive point charge P
On the figure, sketch the electric field pattern around the charge.
Date posted: May 31, 2019. Answers (1)
- A 200g mass of copper was heated to 100°C and then transferred to a lagged copper calorimeter of mass 5g containing 125g of water at...(Solved)
A 200g mass of copper was heated to 100°C and then transferred to a lagged copper calorimeter of mass 5g containing 125g of water at 30°C. Calculate the final temperature of water. (Specific heat capacity of copper = 400J/KgK, water =4200J/KgK).
Date posted: May 31, 2019. Answers (1)
- Figure below shows an object placed 5cm in front of a convex lens whose focus length is 10cm.
a) On the same figure, draw a ray...(Solved)
Figure below shows an object placed 5cm in front of a convex lens whose focus length is 10cm.
a) On the same figure, draw a ray diagram to show the position of the image formed.
b) Use the ray diagram to determine
i) The image distance
ii) The image size
iii) The magnification
Date posted: May 31, 2019. Answers (1)
- The graph below shows how temperature of a 40kg of a substance varied with time as it was heated steadily by electrical
means. The heating coil...(Solved)
The graph below shows how temperature of a 40kg of a substance varied with time as it was heated steadily by electrical
means. The heating coil carried a current of 16A at a potential difference of 22V.
i) What is happening to the substance at AB?
ii) Determine the specific heat capacity of the substance in solid state.
Date posted: May 31, 2019. Answers (1)
- The figure (a) below shows a distance -time graph of a motion of a body.In the figure (b), sketch the corresponding velocity-time graph for the...(Solved)
The figure (a) below shows a distance -time graph of a motion of a body.In the figure (b), sketch the corresponding velocity-time graph for the same motion.
Date posted: May 31, 2019. Answers (1)
- The figure below shows a block diagram of a p-n junction diode.
On the same diagram, show how a cell may be connected so that it...(Solved)
The figure below shows a block diagram of a p-n junction diode.
On the same diagram, show how a cell may be connected so that it is reverse biased.
Date posted: May 31, 2019. Answers (1)
- A bullet is fired from a gun at a velocity of 10m/s. It strikes the tree, perpendicularly and penetrates deeply. If it stops just
as it...(Solved)
A bullet is fired from a gun at a velocity of 10m/s. It strikes the tree, perpendicularly and penetrates deeply. If it stops just
as it emerges through the other side of the tree,
i) Calculate the average retardation if the tree is 2m thick.
ii) Time taken by the bullet in the tree.
Date posted: May 31, 2019. Answers (1)
- The expression below is an equation for a radioactive element P. Element Q and R are the daughter nuclides. P, Q and R are not...(Solved)
The expression below is an equation for a radioactive element P. Element Q and R are the daughter nuclides. P, Q and R are not the actual symbols of any of the elements.
Identify the element R and state two of its characteristics.
Date posted: May 31, 2019. Answers (1)
- A ball is thrown vertically upwards from the ground. It rises up to the highest point and then returns to the ground.Taking
the upward velocity to...(Solved)
A ball is thrown vertically upwards from the ground. It rises up to the highest point and then returns to the ground.Taking
the upward velocity to be positive, sketch the velocity -time graph for the motion.
Date posted: May 31, 2019. Answers (1)
- The mass of the fabric of a large balloon is 100kg. The balloon is inflated with 200cm3 of helium. The balloon is attached to a...(Solved)
The mass of the fabric of a large balloon is 100kg. The balloon is inflated with 200cm3 of helium. The balloon is attached to a cable fixed to the ground as shown.
(Density of air and helium are 1.25kg/m3 and 0.2kg/m3 respectively)
i) Indicate all the forces acting on the system.
ii) If the system is at equilibrium, write an equation relating the three forces in (i) above.
iii) Calculate the upthrust on the balloon.
Date posted: May 31, 2019. Answers (1)
- Explain why most of the x-ray tube is surrounded by lead metal.(Solved)
Explain why most of the x-ray tube is surrounded by lead metal.
Date posted: May 31, 2019. Answers (1)