Explain the applications of junction diodes

Explain the applications of junction diodes.

Answers

They are mainly used for rectification of a.c. current for use by many electrical appliances. Rectification is the conversion of sinusoidal waveform into unidirectional (non-zero) waveform.

1. Half wave rectification
In this case the first half cycle of a sinusoidal waveform is positive and the inclusion of a reverse biased diode makes the current not to flow to the negative side of the wave. The current therefore conducts on every half cycle hence a half wave rectification is achieved.
The voltage is d.c. and always positive in value though it is not steady and needs to be smoothed by placing a large capacitor in parallel to the load as shown.


2. Centre-tap full wave rectification
This is achieved by using a transformer whose output has a centre tap that is taken at two points where one is half the other as shown.


3. Bridge full wave rectification In this case a bridge rectifier is used to achieve a full wave rectification. The current flows in the same direction in both half cycles.


4. Radio transmitter and receiver
Radio waves are produced by circuits that make electrons vibrate and they are known as oscillators which produce varied frequencies. Since radio waves have greater range in air than sound or even light waves they are used as carriers of audio (sound) and visual information (TV) waves.
The sound is first changed into electrical vibrations by use of a microphone or other device then added to the radio carrier wave and this changes the amplitude of the carrier and is called amplitude modulation. The modulated wave is given out by the transmitting aerial and received by another aerial in a radio or TV when they cause vibrations between the earth and the aerial. They are then demodulated by a diode and hence heard as a sound or image.

---

Mutiso answered the question on October 18, 2018 at 18:29

Next: Explain the occurrence of forward bias of a p-n junction and reverse bias of a p-n junction
Previous: Sitaki kazi za uchafu hapa sagamoyo", eleza muktadha wa Dondoo hili katika tamthilia ya Kigogo

View More Physics Questions and Answers | Return to Questions Index

Exams With Marking Schemes

• Grade 1
• Grade 2
• Grade 3
• Grade 4
• Grade 5
• Grade 6
• Grade 7
• Grade 8
• Grade 9
• PP1
• PP2
• Playgroup
• Form 1
• Form 2
• Form 3
• Form 4

Related Questions

• Explain the occurrence of forward bias of a p-n junction and reverse bias of a p-n junction(Solved)
  

  Explain the occurrence of forward bias of a p-n junction and reverse bias of a p-n junction.

  Date posted: October 18, 2018.  Answers (1)

• What are junction diodes?(Solved)
  

  What are junction diodes?

  Date posted: October 18, 2018.  Answers (1)

• What is an intrinsic semiconductor?(Solved)
  

  What is an intrinsic semiconductor?

  Date posted: October 18, 2018.  Answers (1)

• Define the following terms (i) Conductors (ii) Insulators (iii) Semiconductors (Solved)
  

  Define the following terms (i) Conductors (ii) Insulators (iii) Semiconductors

  Date posted: October 18, 2018.  Answers (1)

• Hazards of radioactivity and their precautions(Solved)
  

  Hazards of radioactivity and their precautions

  Date posted: October 17, 2018.  Answers (1)

• A radioactive element has an initial count rate of 2,400 counts per minute on a scaler. The count rate falls to 300 units per minute...(Solved)
  

  A radioactive element has an initial count rate of 2,400 counts per minute on a scaler. The count rate falls to 300 units per minute in 30 hours, (a) Calculate the half-life of the element (b) If the initial number of atoms in another sample of the same element is 6.0 × 1020, how many atoms will have decayed in 50 hours?

  Date posted: October 17, 2018.  Answers (1)

• The initial number of atoms in a sample is 5.12 × 10²⁰. If the half-life of the sample is 3.0 seconds, determine the number of...(Solved)
  

  The initial number of atoms in a sample is 5.12 × 10²⁰. If the half-life of the sample is 3.0 seconds, determine the number of atoms that will have decayed after six seconds.

  Date posted: October 17, 2018.  Answers (1)

• An isotope has a half-life of 576 hours. Complete the following table and show how mass varies with time from an initial mass of 1280...(Solved)
  

  An isotope has a half-life of 576 hours. Complete the following table and show how mass varies with time from an initial mass of 1280 g?
  Time (hrs)----576--1152--1728---2304
  Mass (g)-------640--x------y-----z

  Date posted: October 17, 2018.  Answers (1)

• The half-life of a sample of a radioactive substance is 98 minutes. How long does it take for the activity of the sample to reduce...(Solved)
  

  The half-life of a sample of a radioactive substance is 98 minutes. How long does it take for the activity of the sample to reduce to 1/16^th of the original value?

  Date posted: October 17, 2018.  Answers (1)

• State the law of radioactive decay(Solved)
  

  State the law of radioactive decay

  Date posted: October 17, 2018.  Answers (1)

• Explain ways of detecting nuclear radiation(Solved)
  

  Explain ways of detecting nuclear radiation.

  Date posted: October 17, 2018.  Answers (1)

• Properties of radioactive emissions(Solved)
  

  Properties of radioactive emissions

  Date posted: October 17, 2018.  Answers (1)

• Sodium has a work function of 2.0 e: Calculate (a) The maximum energy and velocity of the emitted electrons when sodium is Illuminated by...(Solved)
  

  Sodium has a work function of 2.0 e: Calculate
  (a) The maximum energy and velocity of the emitted electrons when sodium is Illuminated by a radiation of wavelength 150 nm.
  (b) Determine the least frequency of radiation by which electrons are emitted. (Take ‘h’ = 6.626 × 10-34 Js, e = 1.6 × 10-19, c = 3.0 × 108 m/s and mass of electron = 9.1 × 10-31 kg).

  Date posted: October 17, 2018.  Answers (1)

• The threshold frequency for lithium is 5.5 × 10¹⁴ Hz. Calculate the work function for lithium. (Take ‘h’ = 6.626 × 10^-34 Js)(Solved)
  

  The threshold frequency for lithium is 5.5 × 10¹⁴ Hz. Calculate the work function for lithium. (Take ‘h’ = 6.626 × 10^-34 Js)

  Date posted: October 17, 2018.  Answers (1)

• The work function of tungsten is 4.52 e V. Find the cut-off potential for photoelectrons when a tungsten surface is illuminated with radiation of wavelength...(Solved)
  

  The work function of tungsten is 4.52 e V. Find the cut-off potential for photoelectrons when a tungsten surface is illuminated with radiation of wavelength 2.50 × 10^-7 m. (Planck’s constant, h = 6.62 × 10^-34 Js).

  Date posted: October 17, 2018.  Answers (1)

• The cut-off wavelength for a certain material is 3.310 × 10^-7 m. What is the cut-off frequency for the material?(Solved)
  

  The cut-off wavelength for a certain material is 3.310 × 10^-7 m. What is the cut-off frequency for the material?

  Date posted: October 17, 2018.  Answers (1)

• What is Einstein’s photoelectric equation?(Solved)
  

  What is Einstein’s photoelectric equation?

  Date posted: October 17, 2018.  Answers (1)

• Dangers of X-rays and the precautions(Solved)
  

  Dangers of X-rays and the precautions.

  Date posted: October 16, 2018.  Answers (1)

• An x-ray tube operates at 60 kV and the current through it is 4.0 mA. Calculate the, (a) Number of electrons striking the target per...(Solved)
  

  An x-ray tube operates at 60 kV and the current through it is 4.0 mA. Calculate the, (a) Number of electrons striking the target per second. (b) Speed of the electrons when they hit the target.

  Date posted: October 16, 2018.  Answers (1)

• Determine the energy possessed by X-rays whose frequency is 4 × 10¹⁷ Hz. (Solved)
  

  Determine the energy possessed by X-rays whose frequency is 4 × 10¹⁷ Hz.

  Date posted: October 16, 2018.  Answers (1)