Question

A transmission system at a radio station uses a/an _______ to convert a direct current into a high frequency alternating current.

A. oscillator
B. modulator
C. transmitting antenna
D. demodulator
User: A unit for measuring frequency is the
A. ampere.
B. hertz.
C. ohm.
D. watt.

Answer 1

A transmission system at a radio station consists of essentially the following devices:

1. An oscillator, which converts a direct current into a high-frequency alternating current.

2. A transmitting antenna, which sends out radio waves having the same frequency as the current supplied by the oscillator.

3. A microphone, which picks up the sound waves and converts them into a suitable electric current with the same pattern as the sound waves.

4. A modulator, which enables the waves produced by the antenna to “carry” the pattern of the sound waves picked up by the microphone.

The answer is A. Oscillator

Answer 2

A transmission system at a radio station uses an oscillator to convert a direct current into a high frequency alternating current. Direct current or DC is the current in which the flow of the charge is one directional. In case of alternating current or AC, the flow of the charge reverses direction after a period of time.
In regards to the second question, a unit for measuring frequency is the hertz. So the correct answer to the given question is option “B”.