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GATE-2011 One Mark Questions and Solutions ( Electronic Devices)
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Specially designed for GATE EC Aspirants  Covers previous 10 years (2009-2018) 1 mark questions of Electronic Devices  Detailed solution provided  Related concept has been also explained

AKHILESH PANDEY
B.Tech. in EC, GATE 2017 AIR 18, YouTuber (channel name - STUDENT MODULATOR), 5 years Teaching Experience

U
Unacademy user
mam if any obstacles in path of groundwave propogatin .. means a big hill obstacles in the path of ground wave propogation..then the emw follow the hill path ....and
Akshita Pal
a year ago
I have written there that due to obstacles, diffraction of waves i.e a mechanism happens. So depending on the obstacle the mechanism will change. Also, ground wave is mode of propagation, means a path and not the pattern or way, that is a mechanism. And at points close to earth's surface, there can't be a hill obviously, buildings etc can be there, where I've explained according to the size of obstacles, the mechanism may differ. :)
Navdeep singh
a year ago
ok dear mam tnku a lot u know tht u should make a video of satellite comm.
Navdeep singh
a year ago
ok dear mam tnku a lot u know tht u should make a video of satellite comm.
Akshita Pal
a year ago
Courses on GSM and Satellite Comm. shall be covered soon. Thanks & Welcome :)
Vishal Kumar
7 months ago
hello mam .. if earth works like a capacitor then why it is necessary to wave is propagate along the curvature of earth.. it may be also different
  1. Previous 10 Years (2009-18) 1 Mark Que.&Sol Subject: Electronic Devices Year: 2011 By- AKHILESH PANDEY


  2. About Me BTech. in Electronics & Communication GATE 2017 AIR 18 (EC) 5 Years Teaching Experience Youtuber (channel- STUDENT MODULATOR)


  3. Q.1 Drift current in the semiconductors depends upon (A) only the electric field (B) only the carrier concentration gradient (C) both the electric field and the carrier concentration (D) both the electric field and the carrier concentration gradient


  4. Sol. 1 In a semiconductor, drift current density is defined as (drift current due to electrons) (drift current due to holes) In E ne oE pe ,B where E applied electric field intensity Conductivity n concentration of electrons e Electronic charge Hm, p Mobility of electron/hole


  5. Diffusion current density is defined as where Dn, D - e - Electronic charge dn dx dp dx Diffusion coefficient of electrons/holes Electron concentration gradient Hole concentration gradient Hence, drift current depends on electric field E, while diffusion current depends on carrier concentration gradient.


  6. Q.2 A Zener diode, when used in voltage stabilization circuits, is biased in (A) reverse bias region below the breakdown voltage (B) reverse breakdown region (C) forward bias region (D) forward bias constant current mode


  7. Sol.2 V-I characteristic of zener diode: In forward bias, it works same as the normal diode. In reverse bias, it breakdowns at a lower voltage, called zener breakdown voltage Vz. > After breakdown (reverse bias), voltage is fixed Vz and current increases.


  8. Sol.2 For the Zener diode connected in a voltage stabilization circuit, Iz current through zener diode Vz - voltage across zener diode V Source voltage R - Load resistance Here, after zener breakdown (reverse bias) Vz is fixed and Iz increase with source voltage. Thus, the voltage across load is fixed at V%, independent of the applied source voltage V Thus, Zener diode connected in reverse bias for voltage stabilization.


  9. Q.3 A silicon PN junction is forward biased with a constant current at room temperature. When the temperature is increased by 10 C, the forward bias voltage across the PN junction (A) increases by 60 mV (B) decreases by 60 mV (C) increases by 25 mV (D) decreases by 25 mV


  10. Sol.3 Effect of temperature on V-I characteristics: Case I: Voltage across diode is fixed and temperature is increased Reverse saturation current through a PN junction increases approximately 7% per C for both silicon and germanium. For every 10 C temperature increase, reverse saturation current becomes double (since(1.07)10 2) Case II: Current across diode is fixed and temperature is increased If the temperature is increased, then in order to maintain a constant current value through PN junction, dv 2.5 mW / C dT Hence, for 10 C temperature rise, the voltage decreases by 25 mV