In vibration isolation system, the transmissibility will be equal to unity, for all values of damping factor, if $$\frac{\omega }{{\omega {\text{n}}}}$$ is

The transmissibility, for all values of damping factor, will be less than unity, if $$\frac{\omega }{{\omega {\text{n}}}}$$ is

A

Equal to 1

B

Less than 2

C

Equal to 2

D

Greater than 2

In vibration isolation system, if ω/ωn is less than √2 , then for all values of the damping factor, the transmissibility will be

A

less than unity

B

equal to unity

C

greater than unity

D

zero where ω = Circular frequency of the system in rad/s, and ωn = Natural circular frequency of vibration of the system in rad/s.

In vibration isolation system, if ω/ωn < 2, then for all values of damping factor, the transmissibility will be

A

less than unity

B

equal to unity

C

greater than unity

D

zero

If $$\frac{\omega }{{\omega {\text{n}}}} = 2,$$ where co is the frequency of excitation and $${\omega {\text{n}}}$$ is the natural frequency of vibrations, then the transmissibility of vibration will the

A

0.5

B

1

C

1.5

D

2

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

∞

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

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

Which of the following methods are used for producing damping torque in analog instruments? 1) Air friction damping 2) Fluid friction damping 3) Eddy current damping 4) Electromagnetic damping

A

1, 2 and 3 only

B

1, 2 and 4 only

C

1, 3 and 4 only

D

1, 2, 3 and 4

Which of the following are the basic differences between vibration signature and noise signature? 1. Vibration signature is essentially in the frequency range zero to 100 cps whereas noise signature is in the range 20 cps to 3000 cps. 2. Vibration signature has well-defined peaks whereas the noise signal is smeared. 3. The intensities of noise signatures arc much less than that of vibration signatures. 4. Detection of vibration signature calls for a microphone whereas that of noise can do with a pickup. Select the correct answer using the code given below.

A

1 and 4

B

2 and 3

C

1 and 2

D

3 and 4

In vibration isolation system, if $$\frac{\omega }{{\omega {\text{n}}}}

A

Less than unity

B

Equal to unity

C

Greater than unity

D

Zero

In vibration isolation system, if $$\frac{\omega }{{\omega {\text{n}}}} > 1,$$ then the phase difference between the transmitted force and the disturbing force is

A

0°

B

90°

C

180°

D

270°

In vibration isolation system, the transmissibility will be equal to unity, for all values of damping factor, if $$\frac{\omega }{{\omega {\text{n}}}}$$ is

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