Purpose of Antenna: Receiving Electromagnetic Waves

[kukumaluboy]

Homework Statement

An antenna in RECEIVING mode is a device that

(a) convert electric field to magnetic field
(b) convert high freq current to electromagnetic waves
(c) convert magnetic field to electric field
(d) convert electromagnetic waves to high freq current

(MARK OUT ALL THAT APPLY)

The Attempt at a Solution

My answer was C and D.

But teacher marked me wrong and said the answer was B. Why? I tot transmitting was Current to EM waves. SO receiving should be Em waves to Current rite? And can explain to me about the elec field and magnetic field. Does the antenna convert it?

 

[Ouabache]

Electromagnetic waves (EM waves) are comprised of both electric and magnetic field components. So your teacher is right in discounting answers that discuss conversion from one to another of those fields. However I agree with you, that a receiving antenna converts EM waves to current. EM waves impinge upon the antenna and when the receive switch is turned on, this energy couples into an electric circuit (radio receiver) inducing current to flow. Perhaps you can ask your teacher to explain the reasoning behind her/his answer.

 

[berkeman]

Homework Statement

An antenna in RECEIVING mode is a device that

(a) convert electric field to magnetic field
(b) convert high freq current to electromagnetic waves
(c) convert magnetic field to electric field
(d) convert electromagnetic waves to high freq current

(MARK OUT ALL THAT APPLY)

The Attempt at a Solution

My answer was C and D.

But teacher marked me wrong and said the answer was B. Why? I tot transmitting was Current to EM waves. SO receiving should be Em waves to Current rite? And can explain to me about the elec field and magnetic field. Does the antenna convert it?

I agree with Ouabache. (b) is TX and (d) is RX. The teacher just had a small oopsie.

 

[kukumaluboy]

OK thanks solved. He did mark it wrongly.

 

[DeeNos]

Your answer of C and D is not entirely correct. While it is true that an antenna in receiving mode does convert electromagnetic waves to high frequency current, it also performs the opposite function of converting high frequency current to electromagnetic waves. This is because an antenna is a transducer, which means it can convert one form of energy to another.

To understand this better, let's break down the purpose of an antenna. The main function of an antenna is to capture or receive electromagnetic waves from the surrounding environment. These waves are essentially a combination of electric and magnetic fields oscillating at right angles to each other.

When the electromagnetic waves reach the antenna, they induce a current in the antenna's conductive elements. This is where the conversion of electric field to magnetic field (option A) and magnetic field to electric field (option C) occurs. The electric field of the wave causes the electrons in the antenna to move, creating a magnetic field around the antenna. This magnetic field, in turn, creates an electric field in the antenna, completing the conversion.

The high frequency current generated in the antenna is then sent to a receiver or amplifier, which converts it into a usable form such as sound or images. This is where the conversion of electromagnetic waves to high frequency current (option D) takes place.

So, in summary, an antenna in receiving mode performs the functions of both converting electric field to magnetic field and magnetic field to electric field, as well as converting electromagnetic waves to high frequency current. Therefore, the correct answer to the homework statement is B.