For a multi conductor folded dipole with n conductors, the impedance is ____ Ω.

Lightening conductors are used to protect building from lightning strikes. Which of the following statements is/are true about lightening conductors? 1) Lightening conductors create an electric field at its top that lightning strikes it preferentially 2) Lightning conductors reduce the effect of the strike by uniformly distributing the charge (current) over the surface of the building 3) Lightning conductors take all the charge (current) to deep down in the earth 4) Lightning conductors must be installed at a place taller than the building Select the correct answer using the code given below

A

1 and 2

B

3 and 4 only

C

1, 3 and 4

D

4 only

If the input impedance of a half wave dipole Yagi-Uda is 73Ω, then input impedance of a half wave folded dipole as driven element is ____

A

73Ω

B

146Ω

C

36.5Ω

D

292Ω

Which of the following types of inter molecular interactions or forces is/are called van der Waals forces? 1. London forces 2. Dipole - dipole forces 3. Dipole - induced dipole forces 4. Hydrogen bonding Choose the correct code:

A

Only 2, 3 and 4

B

Only 1, 2 and 3

C

Only 3 and 4

D

Only 1 and 2

Which of the following is/are true about dipole? (1) The unit of electric dipole moment is coulomb meter (2) The net charge of the electric dipole is zero (3) The net electric field due to an electric dipole is nonzero. (4) Point diploe is the diploe with a small value of the charge.

A

Statement 1 & 2 only

B

All the above

C

Statement 1 & 3 only

D

Statement 1 only

A magnetic dipole of dipole moment $$\overrightarrow {\bf{m}} $$ is placed in a non-uniform magnetic field $$\overrightarrow {\bf{B}} .$$ If the position vector of the dipole is $$\overrightarrow {\bf{r}} ,$$ the torque acting on the dipole about the origin is

A

$$\overrightarrow {\bf{r}} \times \left( {\overrightarrow {\bf{m}} \times \overrightarrow {\bf{B}} } \right)$$

B

$$\overrightarrow {\bf{r}} \times \overrightarrow \nabla \left( {\overrightarrow {\bf{m}} .\overrightarrow {\bf{B}} } \right)$$

C

$$\overrightarrow {\bf{m}} \times \overrightarrow {\bf{B}} $$

D

$$\overrightarrow {\bf{m}} \times \overrightarrow {\bf{B}} + \overrightarrow {\bf{r}} \times \overrightarrow \nabla \left( {\overrightarrow {\bf{m}} .\overrightarrow {\bf{B}} } \right)$$

Which of the following causes the shortening effect on multi conductor folded dipole?

A

Only thickness of conductors

B

Space between conductors

C

Radiation resistance of the dipole

D

Both the radii and radiation resistance

Two copper conductors have equal length. The cross-sectional area of one conductor is four times that of the other. If the conductor having smaller cross-sectional area has a resistance of 40 ohms the resistance of other conductor will be

A

160 ohms

B

80 ohms

C

20 ohms

D

10 ohms

An electric field of 1000 V/m is applied to an electric dipole at angle of 45°. The value of electric dipole moment is 10-29 C-m. What is the potential energy of the electric dipole?

A

-9 × 10^-20J

B

-10 × 10^-29 J

C

-20 × 10^-18 J

D

-7 × 10^-27 J

The terminal impedance of a dipole antenna is 710 Ω. The terminal impedance of the slot antenna given the intrinsic impedance of air is 377 Ω is:

A

100 Ω

B

50 Ω

C

25 Ω

D

None of the mentioned

Folded dipole is used than a single dipole in Yagi-Uda to obtain wider frequency range.

A

True

B

False

For a multi conductor folded dipole with n conductors, the impedance is ____ Ω.

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