An n-type semiconductor has an electron concentration of 3 × 1020 m-3. If the electron drift velocity is 100 m/s in an electric field of 200 V/m, the conductivity (in $${\Omega ^{ - 1}}$$ m-1) of this material is

Two monochromatic waves having frequencies $$\omega $$ and $$\omega + \Delta \omega \left( {\Delta \omega \ll \omega } \right)$$ and corresponding wavelengths $$\lambda $$ and $$\lambda - \Delta \lambda \left( {\Delta \lambda \ll \lambda } \right)$$ of same polarization, travelling along X-axis are superimposed on each other. The phase velocity and group velocity of the resultant wave are respectively given by

A

$$\frac{{\omega \lambda }}{{2\pi }},\,\frac{{\Delta \omega {\lambda ^2}}}{{2\pi \Delta \lambda }}$$

B

$$\omega \lambda ,\,\frac{{\Delta \omega {\lambda ^2}}}{{\Delta \lambda }}$$

C

$$\frac{{\omega \Delta \lambda }}{{2\pi }},\,\frac{{\Delta \omega \Delta \lambda }}{{2\pi }}$$

D

$$\omega \Delta \lambda ,\,\omega \Delta \lambda $$

If 30Ω6 = -5, 80Ω2 = -40 and 20Ω4 = -5, then find the value of 70Ω2 = ?

A

10

B

-35

C

15

D

-20

If 7Ω6 = 84, 8Ω7 = 112 and 8Ω4 = 64, then find the value of 3Ω4 = ?

A

24 \

B

12 \

C

4 \

D

20

If 7Ω6 = 84, 8Ω7 = 112 and 8Ω4 = 64, then find the value of 3Ω4 = ?

A

24 \

B

12

C

4 \

D

20

The raised cosine pulse p(t) is used for zero ISI in digital communications. The expression for p(t) with unity roll-off factor is given by $$p\left( t \right) = \frac{{\sin 4\pi \omega t}}{{4\pi \omega t\left( {1 - 16{\omega ^2}{t^2}} \right)}}.$$ The value of p(t) at $$t = \frac{1}{{4\omega }}$$ is

A

-0.5

B

0

C

0.5

D

∞

For a function g(t), it is given that
$$\int\limits_{ - \infty }^{ + \infty } {g\left( t \right){e^{ - j\omega t}}dt = \omega {e^{ - 2{\omega ^2}}}} $$ for any real value $$\omega $$ . If $$y\left( t \right) = \int\limits_{ - \infty }^t {g\left( \tau \right)} d\tau ,\,{\rm{then}}\,\int\limits_{ - \infty }^{ + \infty } {y\left( t \right)} dt$$ is. . . . . . . .

A

0

B

-j

C

$$ - {j \over 2}$$

D

$${j \over 2}$$

The Fourier transform of a signal
h(t) is $$H\left( {j\omega } \right) = {{\left( {2\cos \omega } \right)\left( {\sin \omega } \right)} \over \omega }$$
The value of h(0) is

A

$${1 \over 4}$$

B

$${1 \over 2}$$

C

1

D

2

Two semiconductor material have exactly the same properties except that material A has a bandgap of 1.0 eV and material B has a bandgap energy of 1.2 eV. The ratio of intrinsic concentration of material A to that of material B is

A

2016

B

47.5

C

58.23

D

1048

An electromagnetic wave is propagating in free space in the Z-direction. If the electric field is given by $$E = \cos \left( {\omega t - kz} \right){\bf{\hat i}},$$ where $$\omega t = ck,$$ then the magnetic field is given by

A

$$\overrightarrow {\bf{B}} = \frac{1}{c}\cos \left( {\omega t - kz} \right){\bf{\hat j}}$$

B

$$\overrightarrow {\bf{B}} = \frac{1}{c}\sin \left( {\omega t - kz} \right){\bf{\hat j}}$$

C

$$\overrightarrow {\bf{B}} = \frac{1}{c}\cos \left( {\omega t - kz} \right){\bf{\hat i}}$$

D

$$\overrightarrow {\bf{B}} = \frac{1}{c}\cos \left( {\omega t - kz} \right){\bf{\hat j\hat i}}$$

If the velocity of a charged particle in perpendicular electric and magnetic field is 7.27 X 106m/s and the Electric field is 6 X 106 N/c, what should be the value of magnetic field for velocity sector?

A

0.45 T

B

0.78 T

C

0.83 T

D

0.94 T