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(i)
- lamps are placed in series instead of parallel
- fuse and switch is on the neutral instead of live
(ii)
- fuse is made of a wire with low m.p.
- it safeguards the appliance against damage should the current flowing through i t exceed the safe
limit.
Kavungya answered the question on May 25, 2019 at 07:14
- A transformer has 800 turns in the primary windings. The alternating e.m.f connected to the primary
is 240V and the current flowing is 0.2A. Find the...(Solved)
A transformer has 800 turns in the primary windings. The alternating e.m.f connected to the primary
is 240V and the current flowing is 0.2A. Find the power in the secondary coil if the transformer is 90% efficient
Date posted: May 25, 2019. Answers (1)
- The figure below shows a bridge rectifier.
i) Define the term rectification.
ii) Describe how the illustrated rectifier works.
iii) State the modification that can...(Solved)
The figure below shows a bridge rectifier.
i) Define the term rectification.
ii) Describe how the illustrated rectifier works.
iii) State the modification that can be made on the arrangement to improve the quality of the output.
Date posted: May 25, 2019. Answers (1)
- Calculate the photon energy in ultraviolet radiation whose frequency is 8.60 x 1014 Hz. (Plank’s constant h=6.63 x 10-34 Js)(Solved)
Calculate the photon energy in ultraviolet radiation whose frequency is 8.60 x 1014 Hz. (Plank’s constant h=6.63 x 10-34 Js)
Date posted: May 25, 2019. Answers (1)
- In an experiment to find the relationship between frequency of radiation and kinetic energy of photoelectrons in a photoelectric device, the following graph was obtained.
Use...(Solved)
In an experiment to find the relationship between frequency of radiation and kinetic energy of photoelectrons in a photoelectric device, the following graph was obtained.
Use the graph to answer the following questions,
i) Determine the threshold frequency.
ii) Find the plank's constant h. .(Take the charge of an electron to be 1.6 x 10-19 C)
iii) Calculate the work function of the metal in joules.
Date posted: May 25, 2019. Answers (1)
- A wire of resistance 27 ohms is cut into three equal lengths. If the three wires are connected in parallel, what is the effective resistance?(Solved)
A wire of resistance 27 ohms is cut into three equal lengths. If the three wires are connected in parallel, what is the effective resistance?
Date posted: May 25, 2019. Answers (1)
- The initial mass of a radioactive substance is 40g. The substance has a half-life of 10 years. Determine the mass remaining after 40 years.(Solved)
The initial mass of a radioactive substance is 40g. The substance has a half-life of 10 years. Determine the mass remaining after 40 years.
Date posted: May 25, 2019. Answers (1)
- The graph below shows the displacement of a pendulum bob from its rest position as it varies with time.
What is the frequency of the pendulum?(Solved)
The graph below shows the displacement of a pendulum bob from its rest position as it varies with time.
What is the frequency of the pendulum?
Date posted: May 25, 2019. Answers (1)
- Sketch the magnetic field pattern of the following arrangement.(Solved)
Sketch the magnetic field pattern of the following arrangement.
Date posted: May 25, 2019. Answers (1)
- A sharp point of a pin is held over a positively charged electroscope. State and explain the observation made on the electroscope.(Solved)
A sharp point of a pin is held over a positively charged electroscope. State and explain the observation made on the electroscope.
Date posted: May 25, 2019. Answers (1)
- The figure below shows a ray of light incident on a glass prism.
Given that the critical angle for the glass is 390, sketch on the...(Solved)
The figure below shows a ray of light incident on a glass prism.
Given that the critical angle for the glass is 390, sketch on the diagram the path of the ray through the prism.
Date posted: May 25, 2019. Answers (1)
- State why parabolic reflectors are used in car headlights(Solved)
State why parabolic reflectors are used in car headlights.
Date posted: May 22, 2019. Answers (1)
- The figure below shows an object O placed infront of a converging mirror of local length
15cm.
Draw on the figure a ray diagram to locate the...(Solved)
The figure below shows an object O placed infront of a converging mirror of local length
15cm.
Draw on the figure a ray diagram to locate the image formed.
Date posted: May 22, 2019. Answers (1)
- The figure below shows the path of a ray of light through a glass prism. The speed of yellow
light in the prism is 1.88 ×...(Solved)
The figure below shows the path of a ray of light through a glass prism. The speed of yellow
light in the prism is 1.88 × 108m/s.
(i) Determine the refractive index of the prism material for the light (speed of light in vacuum, c
= 3.0 × 108m/s.
(ii) Show on the figure, the critical angle, c, and determine its value.
(iii) Given that r = 21.2º, determine the angle θ.
Date posted: May 22, 2019. Answers (1)
- The echo sounder of a ship receives the reflected wave from a sea-bed after 0.2 seconds.
What is the depth of the sea bed if the...(Solved)
The echo sounder of a ship receives the reflected wave from a sea-bed after 0.2 seconds.
What is the depth of the sea bed if the velocity of sound in water is 1450m/s.
Date posted: May 22, 2019. Answers (1)
- The diagram below represents a wave motion.
(i) What is the amplitude of the wave in metres.
(ii) How many cycles are made.
(iii)Calculate the wavelength of...(Solved)
The diagram below represents a wave motion.
(i) What is the amplitude of the wave in metres.
(ii) How many cycles are made.
(iii)Calculate the wavelength of the wave.
(iv) Calculate the frequency of the wave.
(v) Calculate the velocity of the wave.
Date posted: May 22, 2019. Answers (1)
- Study the circuit below and answer the questions that follow.
(i) Determine the effective resistance of the circuit.
(ii) Find the ammeter reading.
(iii)Find the p.d between...(Solved)
Study the circuit below and answer the questions that follow.
(i) Determine the effective resistance of the circuit.
(ii) Find the ammeter reading.
(iii)Find the p.d between X and Y.
(iv) State the factors that affect the resistance of a conductor.
Date posted: May 22, 2019. Answers (1)
- In an experiment to determine the internal resistance of a cell, the following circuit was used.
It was noted that when S is open, the voltmeter...(Solved)
In an experiment to determine the internal resistance of a cell, the following circuit was used.
It was noted that when S is open, the voltmeter reads 1.5V and when S is closed the voltmeter reads 1.3V and ammeter reads 0.2A.
(i) What is the e.m.f of the cell.
(ii) Determine the lost voltage.
(iii)Find the value of R.
(iv) Find the internal resistance of the cell.
Date posted: May 22, 2019. Answers (1)
- The force on a straight conductor carrying current in a magnetic field can be varied by changing, among others, the magnitude of the current and...(Solved)
The force on a straight conductor carrying current in a magnetic field can be varied by changing, among others, the magnitude of the current and the magnetic field strength. Name the other factors that can be changed to vary the force.
Date posted: May 22, 2019. Answers (1)
- The figure below shows two incident rays on a concave mirror from the top of an object.
Complete the ray diagram showing the reflected rays.
(Solved)
The figure below shows two incident rays on a concave mirror from the top of an object.
Complete the ray diagram showing the reflected rays.
Date posted: May 22, 2019. Answers (1)
- A car accumulator is rated 40Al and is expected to supply a constant current for 120 minutes. Calculate the amount of current delivered.(Solved)
A car accumulator is rated 40Al and is expected to supply a constant current for 120 minutes. Calculate the amount of current delivered.
Date posted: May 22, 2019. Answers (1)