When Hertzian dipole is connected to a practical antenna, which of the following fields is observed to be absent when a uniform current flow is observed?

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 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

The radiation pattern of Hertzian dipole in the plane perpendicular to dipole is a

A

Null

B

Circle

C

Figure of eight

D

None of the above

If the radiation resistance of a Hertzian dipole is 100Ω, then the radiation resistance of short dipole is ____Ω.

A

25

B

50

C

73

D

35.6

When an electric current coil of a wattmeter is connected to the electric current path R and the voltage coil is connected between the electric current R path and the neutral side of the balanced three phase supply, it shows 10 kW. The line voltage along the phase sequence RYB is 400 V. The current drawn by the current path is 54 A. What is the new reading of the wattmeter if the voltage coil is connected between the lines B and the Y paths, even if the electric current coil is continuously present in the line R?

A

13 kW

B

0

C

-13 kW

D

20 kW

Hertzian dipole carries which type of current throughout its length while radiating?

A

Varying

B

Constant

C

Depends on type of polarization

D

Depends on radiation resistance

Flow at constant rate through a tapering pipe is
i) steady flow
ii) uniform flow
iii) unsteady flow
iv) non-uniform flow
The correct answer is

A

(i) and (ii)

B

(i) and (iv)

C

(ii) and (iii)

D

(ii) and (iv)

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

A Hertzian dipole consists of two _____ and ______ charges separated by a very short distance.

A

unequal, opposite

B

equal, same

C

equal, opposite

D

unequal, same

When Hertzian dipole is connected to a practical antenna, which of the following fields is observed to be absent when a uniform current flow is observed?

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