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भारतीय रसायन के पिता आचार्य प्रफुल्ल चंद्र रे की जयंती पर व्याख्यान का आयोजन

भारतीय रसायन के पिता आचार्य प्रफुल्ल चंद्र रे की जयंती पर व्याख्यान का आयोजन विज्ञान भारती उदयपुर इकाई एवं बीएन कॉलेज ऑफ फार्मेसी, बीएन विश्वविद्यालय के संयुक्त तत्वावधान में कार्यक्रम सम्पन्न उदयपुर, 2 अगस्त। भारतीय रसायन के पिता आचार्य प्रफुल्ल चंद्र रे की जयंती के अवसर पर विज्ञान भारती उदयपुर इकाई (चित्तौड़ प्रांत) एवं बीएन कॉलेज ऑफ फार्मेसी, बीएन विश्वविद्यालय के संयुक्त तत्वावधान में एक विशेष व्याख्यान का आयोजन किया गया। कार्यक्रम का उद्देश्य आचार्य पी.सी. रे के वैज्ञानिक योगदान एवं उनके देशभक्ति से ओतप्रोत जीवन पर प्रकाश डालना था। ज्ञातव्य है कि भारत की पहली फार्मा कंपनी आचार्य रे ने ही बंगाल केमिकल एंड फार्मास्यूटिकल्स लिमिटेड, कोलकाता में 1901 में प्रारंभ की थी। कार्यक्रम में विज्ञान भारती के उद्देश्य एवं गतिविधियों की जानकारी डॉ. अमित गुप्ता द्वारा दी गई। आचार्य पी.सी. रे के जीवन और कार्यों पर मुख्य व्याख्यान डॉ. लोकेश अग्रवाल द्वारा प्रस्तुत किया गया। उन्होंने बताया कि कैसे आचार्य रे ने विज्ञान को समाज की सेवा का माध्यम बनाया और रसायन विज्ञान में भारत को आत्मनिर्भर बनान...
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Half wave rectifier | Electronics | Power supply

Half wave rectifier

Rectifier

  • A device which is used to convert alternating current (or voltage) into direct current (or voltage) is known as rectifier
  • The process of converting ac into dc is known as rectification.

Principle of rectifier

  • A diode offers a low resistance in forward bias and a high resistance in reverse bias.
  • It means a very small or practically a zero current flows through the circuit, when diode is reverse biased. This principle is used in the working of rectifier.

Half wave rectifier (HWR)

  • A rectifier which converts only half cycle of input ac into dc is known as half wave rectifier.

  • In this rectifier an alternating voltage E = E0 sin ωt is applied at the primary coil of transformer.
  • The output voltage is always positive, but it does not remain constant with respect to time.
  • The output voltage obtained will be pulsating dc voltage.
  • If Rf = forward dynamic resistance of diode, Rs = resistance of secondary coil of transformer, and RL = load resistance, then
  • Current flowing through RL

Average value of output pulsating current/voltage


Average value of voltage across RL


Root mean square value of pulsating current/voltage

  • For a complete cycle of input, the square root of mean of square of current is root mean square (rms) value of current.


Root mean square value of output voltage


Power supplied to the circuit

  • Input ac power = Power across Rs + Power across diode resistance Rf + Power across RL

Average power supplied to the load

  • Output dc power in load RL

Efficiency of half wave rectifier

  • It is defined as the ratio of the output dc power to the input ac power.
  • η = (output dc power / input ac power) × 100 %

  • By increasing the value of load resistor RL, the value of rectifier efficiency increases.
  • When RL >> R, ηmax = 40.6 %
  • When RL = R, η = 20.3 %

Ripple factor (r)

  • The output voltage or current obtained from rectifier is unidirectional, but its value does not remain constant with time.
  • The pulsation available in the output current or voltage is ripples.
  • Ripple factor gives the measure of smoothing of output voltage or current of a rectifier.
  • r = effective value of output ac component / Average of dc component of output current = Iac / Idc
  • From ac circuit theory

  • Thus half wave rectifier is a poor device for converting ac into dc

Voltage regulation (VR)

  • The strength of maintaining a constant voltage by a rectifier on varying the load resistance is voltage regulation.
  • VR = [(VNL - VFL) / VFL ] × 100%
  • VNL = Output in the absence of load resistance (when RL = ∞)
  • VFL = Output in the presence of load resistance
  • For ideal power supply VR = 0
  • It means in ideal power supply the output voltage should not depend on load.


  • As the value of Idc increases, the value of Edc decreases linearly.

Peak inverse voltage (PIV)

  • The maximum value of voltage which is withstand on the diode, when no current is flowing in the circuit.
  • It is the maximum voltage on the diode in its non-conducting state.
  • For half wave rectifier, PIV = - E0

Frequency component of output voltage or current

  • From Fourier analysis, the output current

  • First term I0 / π represents the dc or average value of current
  • Frequency of second term is equal to the frequency of input ac voltage and its peak value is I0 / 2
  • The other terms represents the harmonics.
To know more about half wave rectifier please visit on https://youtu.be/ZOGVLxLFWxU
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