Draw a circuit diagram of a common emitter amplifier using n-p-n transistor. Derive an expression for the current gain $\beta_{ac}.$
CBSE OUTSIDE DELHI - SET 2 SOUTH 2016
Download our app for free and get startedPlay store
  1.  
  1. $\text{A}_{v} = \beta_{ac}.\frac{\text{R}_{L}}{\text{r}}$
$\therefore\beta_{ac} = \text{A}_{c}\frac{\text{r}}{\text{R}_{L}}$
Alternate Answer
$\beta_{ac} = \frac{\delta\text{l}_{c}}{\Delta\text{I}_{B}}$
art

Download our app
and get started for free

Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*

Similar Questions

  • 1
    In what way is Gauss’s law in magnetism different from that used in electrostatics? Explain briefly. The Earth’s magnetic field at the Equator is approximately 0.4 G. Estimate the Earth’s magnetic dipole moment. Given: Radius of the Earth = 6400 km.
    View Solution
  • 2
    What is the power dissipated in an ac circuit in which voltage and current are given by $\text{V}=230\sin(\omega\text{t}+\frac{\pi}{2})$ and $\text{I}=10\sin\omega\text{t}?$
    View Solution
  • 3
    When an inductor L and a resistor R in series are connected across a 12 V, 50 Hz supply, a current of 0.5 A flows in the circuit. The current differs in phase from applied voltage by $\pi/3$ radian. Calculate the value of R.
    View Solution
  • 4
    In the given circuit, the potential difference across the inductor L and resistor R are 200V and 150V respectively and the rms. value of current is 5A. Calculate (i) the impedance of the circuit and (ii) the phase angle between the voltage and the current.
    View Solution
  • 5
    An AC source of voltage $\text{V = Vm}\sin\omega\text{t}$ is applied across a series LCR circuit. Draw the phasor diagrams for this circuit, when,
    1. Capacitive impedance exceeds the inductive impedance.
    2. Inductive impedance exceeds capacitive impedance.
    View Solution
  • 6
    Figure shows a light bulb (B) and iron cored inductor connected to a dc battery through a switch (S).
    1. What will one observe when switch (S) is closed?
    2. How will the glow of the bulb change when the battery is replaced by an ac source of rms voltage equal to the voltage of dc battery? Justify your answer in each case.
    View Solution
  • 7
    Half life of $^{238}\text{U}_{92}$against$\alpha$ decay is $4.5 \times 10^{9}$years. Calculate the activity of Ig sample of$^{238}\text{U}_{92}$? Given Avogadro's number $= 6 \times 10^{26}$atoms/kmol.
    View Solution
  • 8
    Two harmonic waves of monochromatic light$\text{y}_{1} = \text{a} \cos\omega\text{t}\text{ and } \text{y}_{2} = \text{a} \cos(\omega\text{t} + \Phi)$
    are superimposed on each other. Show that maximum intensity in interference pattern is four times the intensity due to each slit. Hence write the conditions for constructive and destructive interference in terms of the phase angle$\Phi$.
    View Solution
  • 9
    In a series LCR circuit, $\text{R = 1k}\Omega,\text{C}=2\mu\text{F}$ and voltage across R is 100V. The resonant frequency of the circuit $\omega$ is 200 rad $s^{-1}$. Calculate the value of voltage across L at resonance.
    View Solution
  • 10
    An inductor 200 mH, capacitor 500 µF, resistor 10Ω are connected in series with a100 V, variable frequency a.c. source. Calculate the
    1. Frequency at which the power factor of the circuit is unity.
    2. Current amplitude at this frequency.
    3. Q-factor.
    View Solution