Tag: physics

Questions Related to physics

The most energetic electromagnetic radiations are:

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. microwaves

  2. ultraviolet waves

  3. $X$-rays

  4. gamma rays

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Correct Option: D
Explanation:

Gamma rays are the most energetic light waves found on the electromagnetic spectrum.

Microwaves are detected by

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. barometer

  2. point contact diodes

  3. thermopiles

  4. the eye

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Correct Option: B
Explanation:

Point contact diodes, commonly called crystals, are the oldest microwave semiconductor devices. Unlike the pn-junction diode, the point-contact diode depends on the pressure of contact between a point and a semiconductor crystal for its operation.One section of the diode consists of a small rectangular crystal of n-type silicon. A fine beryllium-copper, bronze-phosphor, or tungsten wire presses against the crystal and forms the other part of the diode During the manufacture of the point contact diode, a relatively large current is passed from the the wire to the silicon crystal. The result of this large current is the formation of a small region of p-type material around the crystal in the vicinity of the point contact. Thus, a pn-junction is formed which behaves in the same way as a normal pn-junction. The pointed wire is used instead of a flat metal plate to produce a high-intensity electric field at the point contact without using a large external source voltage.

State whether given statement is True or False

MRI uses radio-waves.

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body.

Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field temporarily realigns hydrogen atoms in your body. Radio waves cause these aligned atoms to produce very faint signals, which are used to create cross-sectional MRI images like slices in a loaf of bread.

Radio waves with frequencies higher than television signals are

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. ultrasonic waves

  2. sound waves

  3. light waves

  4. microwaves

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Correct Option: D
Explanation:

The frequency of television signal is smaller than that of microwave and visible waves.

Radio waves do not penetrate in the band of

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. ionosphere

  2. mesosphere

  3. troposphere

  4. stratosphere

Show answer
Correct Option: A
Explanation:

$Answer:-$ A option

The ionization of gas particles in the ionosphere aids in the transmission of radio waves by reflecting waves back to Earth, rather than allowing them to escape the atmosphere. Solar flares, the spontaneous eruption of high-energy radiation from the surface of the sun, can cause a sharp increase in the number of ionized particles in the upper atmosphere and can interfere with radio wave transmissions.

A radar sends the waves towards a distant object and receives the signal reflected by object. These waves are

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. sound waves

  2. light waves

  3. radio waves

  4. microwaves

Show answer
Correct Option: C,D
Explanation:

$Answer:-$ C and D option

A radar system consists of a transmitter producing electromagnetic waves in the radio or microwave domain, an emitting antenna, a receiving antenna (separate or the same as the previous one) to capture any returns from objects in the path of the emitted signal, a receiver and processor to determine properties of the object(s).

Fluorescent tubes give more light than a filament bulb of same power because

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. the tube contains gas at low temperature

  2. ultraviolet light is converted into visible light by fluorescence

  3. light is diffused through the walls of the tube

  4. it produces more heat than bulb

Show answer
Correct Option: B
Explanation:

The tubelight has coating of fluorescent material which converts ultra violet light into visible light. Hence the light is more intense. 

For transmission of speeches, talks, music, dramas etc ........... is used

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. radio broadcast transmitter

  2. radio telegraph transmitter

  3. navigation transmitter

  4. None of these

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Correct Option: A
Explanation:

$Answer:-$ A

Radio Broadcast Transmitters: -Theses transmitters are designed for transmitting speeches, talks, music, dramas etc for the information and reception of people. These broadcast transmitters may be either amplitude modulated or frequency modulated. The A.M transmitters operate on long waves, medium waves and short waves and radiate carrier power as low as about 1 kW and high as 100 kW. The F.M broadcast transmitters operate on very short waves or on ultra waves and radiate carrier power of the order of 100 kW or so.

Astronauts communicate with one another on moon with the help of.

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. radio waves

  2. sound waves

  3. ultrasound waves

  4. infrasound waves

Show answer
Correct Option: A
Explanation:

Answer is A.

Astronauts communicate with each other in space when they are spacewalking through the use of radio waves. Radio wave signal are sent to their headsets which then translates the signal into the form of sound . When receiving and sending message to earth it is sent in the form of radio waves which is then translated to sound wave (message) by a radio set. 

In which one of the following regions of the electromagnetic spectrum will the vibrational motion of molecules give rise to absorption?

physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

  1. Ultraviolet

  2. Microwaves

  3. Infrared

  4. Radio waves

Show answer
Correct Option: B
Explanation:

Molecular spectra due to vibrational motion lie in the microwave region of electromagentic spectrum. Due to Kirchhoff's law in spectroscopy the same will be absorbed.