In two transistor model of an SCR the expression for anode current is given by:
\(\frac{\alpha_2 I_g}{1-(\alpha_1+\alpha_2)}\)
The question is about finding the expression for the anode current in the two transistor model of a Silicon Controlled Rectifier (SCR).
The two-transistor model of an SCR consists of two transistors: one PNP and one NPN. This model is used to explain the working of SCRs. The expressions of current in this model are crucial for understanding how an SCR functions.
Let's evaluate the given options:
- The anode current \( I_a \) in terms of transistor currents is given by the expression derived from the current gain of the two transistors:
- The relationship for the anode current in the two-transistor model of an SCR is:
\(I_a = \frac{I_g + \alpha_2 I_a}{1 - \alpha_1 - \alpha_2}\)
where:
- \(\alpha_1\) and \(\alpha_2\) are the current gains of the transistors.
- \(I_g\) is the gate current.
Solving the above equation for \(I_a\), we get:
\(I_a = \frac{\alpha_2 I_g}{1-(\alpha_1+\alpha_2)}\)
This matches the given correct answer option:
\(\frac{\alpha_2 I_g}{1-(\alpha_1+\alpha_2)}\)
Conclusion: The correct expression for the anode current in the SCR model is derived correctly based on the two-transistor theory, leading to the choice of our answer.
Similar Questions
Which of the following statements are true for SCR ?
(a) UJT is a phase controlling device for SCR rectifier.
(b) The average load voltage of SCR rectifier is greater than average load voltage of ordinary diode rectifier.
(c) Power delivered to the load in SCR rectifier is maximum when SCR firing angle is zero degree.
(d) SCR can control the amount of power fed to the load by switching current OFF and ON upto many thousand times a second.
Match the following lists :
List - I List - II a. SCR can be turned off by i. it turns off when anode current falls below this value. b. Turn on time of SCR can be reduced by ii. the rectangular pulse of high amplitude and narrow width c. Holding current for an SCR means iii. its anode current interruption d. A forward current can be applied to an SCR after iv. its gate recovery time Correct Codes are :
The voltage safety factor (Vf) of a thyristor is given by :
In SCR, the following statements are given :
(a) It acts as a short circuit device.
(b) It acts as an open circuit device.
(c) ON state voltage is approximately 2-5 Volts.
(d) ON state voltage is approximately 50-100 Volts.
Which of the above statements are correct ?
An SCR is turned off by :
For a two transistor model, the value of α1 + α2 is equal to :
Important Questions from Thyristors
_______ is the device which acts like an N-P-N and a P-N-P transistor connected base-to-base and emitter-to-collector.
SCR stands for
A conducting SCR can be opened by reducing __________to zero.
Which of the following statements correctly describes the structure of a Silicon Controlled Rectifier (SCR)?
The thyristors which have a turn-off time less than _________ are called inverter grade thyristors.
