Download App

Semiconductors and Semiconductor Devices — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsSemiconductors and Semiconductor Devices1 Mark
Question
Two identical capacitors A and B are charged to the same potential V and are connected in two circuits at t = 0 as shown in figure. The charges on the capahltors at a time t = CR are, respectively:

  1. $\text{VC}, \text{VC}$
  2. $\frac{\text{VC}}{\text{e}}, \text{VC}$
  3. $\text{VC}, \frac{\text{VC}}{\text{e}}$
  4. $\frac{\text{VC}}{\text{e}}, \frac{\text{VC}}{\text{e}}$
✓

Answer

  1. $\frac{\text{VC}}{\text{e}}, \text{VC}$

Explanation:

In circuit (a), the diode is forward biassed. So, it offers negligible resistance to the flow of current and can thus be replaced by a short circuit. Now, the capacitor charge will leak through the resistance and decay exponentially with time.

Capacitor charge $=\frac{\text{VC}}{\text{e}}$

In circuit (b), the diode is reverse biassed. So, it offers infinite resistance to the current flow and can thus be replaced by an open circuit. As the circuit is open now, no current can flow across the resistance. So, the charge in the capacitor cannot leak through the resistor.

Capacitor charge = VC

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q [1M]" from Semiconductors and Semiconductor Devices→Semiconductors and Semiconductor Devices — all question types→Physics STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

There is a current of 20 amperes in a copper wire of  square metre area of cross-section. If the number of free electrons per cubic metre is , then the drift velocity is

(a) 125  

(b) 12.5  

(c) 1.25  

(d) 1.25  
→
Two projectiles A and B are projected with angle of projection 15° for the projectile A and 45° for the projectile B. If RA and RB be the horizontal range for the two projectiles, then:
  1. RA < RB
  2. RA = RB
  3. RA > RB
  4. The information is insufficient to decide the relation of RA with RB.
→

An electromagnetic wave of frequency v = 3.0MHz  passes from vacuum into a dielectric medium with permittivity ε = 4.0 . Then

(a) Wavelength is doubled and the frequency remains unchanged

(b) Wavelength is doubled and frequency becomes half

(c) Wavelength is halved and frequency remains unchanged

(d) Wavelength and frequency both remain unchanged
→
Magnetic field intensity is defined as:
→
The ground state energy of hydrogen atom is -13.6 eV. The kinetic and potential energies of the electron in this state are:
→

A and B are two conductors carrying a current i in the same direction. x and y are two electron beams moving in the same direction

(a) There will be repulsion between A and B attraction between x and y

(b) There will be attraction between A and B, repulsion between x and y

(c) There will be repulsion between A and B and also x and y

(d) There will be attraction between A and B and also x and y
→
A shell is fired from a cannon with a velocity V at an angle $\theta$ with the horizontal direction. At the highest point in its path, it explodes into two pieces of equal masses. One of the pieces retraces its path to the cannon. The speed of the other piece immediately after the explosion is:

  1. $\text{3V}\cos\theta$

  2. $2\text{V}\cos\theta$

  3. $\frac{3}{2}\text{V}\cos\theta$

  4. $\text{V}\cos\theta$

→

The maximum efficiency of full wave rectifier is

(a) 100% 

(b) 25.20%

(c) 40.2%

(d) 81.2%
→

The drift velocity of free electrons in a conductor is ‘v’ when a current ‘i’ is flowing in it.  If both the radius and current are doubled, then drift velocity will be

(a) v

(b)  

(c)  

(d)  
→
The instantaneous magnitude of magnetic flux associated with a closed circuit of $5 \Omega$ resistance is given by $\phi_{ B }=6 t^2-5 t+1$, then magnitude of induced current (in A ) in the circuit at $t =0.25$ second is :
→