Practice MCQ Questions and answers on Physics-GK

If a carrier wave of 1000 kHz is used to carry the signal, the length of transmitting antenna will be equal to 300 m.

Wireless communication is the transfer of information between two or more points that are not connected by an electrical conductor. With radio waves distances can be short, such as a few metres for television remote control, or as far as thousands or even millions of kilometres for deep-space radio communications.

A television channel is a physical or virtual channel over which a television station or television network is distributed. Channel numbers represent actual frequencies used to broadcast the television signal. For example, in North America, “channel 2” refers to the broadcast or cable band of 54 to 60 MHz, with carrier frequencies of 55.25 MHz for NTSC analog video (VSB) and 59.75 MHz for analog audio (FM), or 55.31 MHz for digital ATSC (8VSB).

Frequency modulation (FM) conveys information over a carrier wave by varying its instantaneous frequency. This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant. Frequency modulation is also used in telemetry, radar, seismic prospecting and newborn EEG seizure monitoring. Frequency modulation is known as phase modulation when the carrier phase modulation is the time integral of the FM signal. FM is widely used for broadcasting music and speech, two-way radio systems, magnetic taperecording systems and some video-transmission systems.

Positive feedback is used in oscillators.

A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum. Cathode ray oscilloscope is an electronic display device containing cathode-ray tube (CRT) that generates an electron beam that is used to produce visible patterns or graphs on a phosphorescent screen. A sonometer is an apparatus made of hollow box having two holes. A string is attached to it by which the transverse vibrations of strings can be studied.

All automobiles uses satellite communication channel for their GPS devices.

In a optical fibre cable, the signal is propagated along the inner core.

In Analog TV broadcast, Audio signals are transmitted by Frequency Modulation (FM), while video signals are transmitted by Amplitude Modulation (AM).

The lower atmosphere is more or less transparent to radio waves. However, the ionosphere reflects back the radio waves. Thus, a signal emitted by an antenna from a certain place can be received at another place on the surface of Earth in the following two ways: ground wave propagation and sky wave propagation.