Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Electronic Devices question

2019 · 9 Jan · Shift 1 · Q45
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Physics
  4. /Electronic Devices
  5. /2019 · 9 Jan · Shift 1 · Q45

Electronic Devices question

2019 · 9 Jan · Shift 1 · Q45

JEE MainPhysicsElectronic DevicesMCQ+4 / −1
Mobility of electrons in a semiconductor is defined as the ratio of their drift velocity to the applied electric field. If, for an n-type semiconductor, the density of electrons is 1019 m −-− 3 and their mobility is 1.6 m2/(V.s) then the resistivity of the semiconductor (since it is an n-type semiconductor contribution of holes is ignored) is close to :
  1. A
    2 Ω2\,\Omega2Ω m
  2. B
    4  Ω\,\OmegaΩ m
  3. C
    0.4  Ω\,\OmegaΩ m
  4. D
    0.2  Ω\,\OmegaΩ m
View written solutionFree

Correct answer: C

  1. Use conductivity formula for an n-type semiconductor

For an n-type semiconductor, ignoring holes,

σ=neμe\sigma = n e \mu_eσ=neμe​

where:

  • n=1019 m−3n = 10^{19}\,\text{m}^{-3}n=1019m−3
  • e=1.6×10−19 Ce = 1.6 \times 10^{-19}\,\text{C}e=1.6×10−19C
  • μe=1.6 m2/(V⋅s)\mu_e = 1.6\,\text{m}^2/(\text{V·s})μe​=1.6m2/(V⋅s)
  1. Calculate conductivity
σ=(1019)(1.6×10−19)(1.6)\sigma = (10^{19})(1.6 \times 10^{-19})(1.6)σ=(1019)(1.6×10−19)(1.6)

First,

1019×1.6×10−19=1.610^{19} \times 1.6 \times 10^{-19} = 1.61019×1.6×10−19=1.6

So,

σ=1.6×1.6=2.56 S/m\sigma = 1.6 \times 1.6 = 2.56\,\text{S/m}σ=1.6×1.6=2.56S/m
  1. Find resistivity

Resistivity is the reciprocal of conductivity:

ρ=1σ=12.56\rho = \frac{1}{\sigma} = \frac{1}{2.56}ρ=σ1​=2.561​ ρ≈0.39 Ω m\rho \approx 0.39\,\Omega\,\text{m}ρ≈0.39Ωm
  1. Choose the closest option
ρ≈0.4 Ω m\rho \approx 0.4\,\Omega\,\text{m}ρ≈0.4Ωm

So the correct option is C.

PreviousNext

More from Electronic Devices

  • Ge and Si diodes start conducting at 0.3 V and 0.7 V respectively. In the following figure if Ge diode connection are reversed, the value of V0 changes by : (assume that the Ge diode has large breakdown voltage) Includes diagram2019 · MCQ
  • The figure represents a voltage regulator circuit using a Zener diode. The breakdown voltage of the Zener diode is 6 V and the load resistance is, RL = 4k Ω. The series resistance of the circuit is Ri = 1 k Ω. If the battery… Includes diagram2019 · MCQ
  • To get output 1 at R, for the given logic gate circuit the input values must be Includes diagram2019 · MCQ
  • For the circuit shown below, the current through the Zener diode is - Includes diagram2019 · MCQ
  • In the given circuit the current through Zener Diode is close to: Includes diagram2019 · MCQ
  • The circuit shown below contains two ideal diodes, each with a forward resistance of 50 Ω. If the battery voltage is 6 V, the current through the 100 Ω resistance (in Amperes) is : Includes diagram2019 · MCQ
  • The truth table for the circuit given in the fig. is: Includes diagram2019 · MCQ
  • Figure shows a DC voltage regulator circuit, with a Zener diode of breakdown voltage = 6V. If the unregulated input voltage varies between 10 V to 16 V, then what is maximum Zener current? Includes diagram2019 · MCQ