Physics

Electromagnetic Waves and Spectrum

670 Questions

Electromagnetic waves and spectrum questions test a candidate's understanding of radiation frequencies, wavelengths, and the properties of different rays like infrared, ultraviolet, and visible light. Concepts also cover practical applications in astronomy and the fundamental speed of light calculations. This physics topic appears regularly in general science sections of major competitive examinations.

UV rays propertiesElectromagnetic radiation frequencyWavelength identificationSpeed of light calculationsBlack body radiation

Electromagnetic Waves and Spectrum Questions

Multiple choice general knowledge science & technology

What is the Speed of light?

  1. 300,000 Mt/Sec

  2. 30000 Km/Sec

  3. 300,000 Km/Sec

  4. None of above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

To solve this question, the user needs to know the definition of the speed of light.

The speed of light is defined as the distance light travels in a vacuum per unit of time.

Now, let's go through each option and explain why it is right or wrong:

A. 300,000 Mt/Sec: This option is incorrect because "Mt" is not a standard unit of measurement for speed. Also, the correct value of the speed of light is 299,792.458 km/s, which is not equal to 300,000 Mt/Sec.

B. 30000 Km/Sec: This option is incorrect because the actual value of the speed of light is much greater than 30,000 km/s. The correct value is around 299,792.458 km/s.

C. 300,000 Km/Sec: This option is correct. The speed of light in a vacuum is approximately 299,792.458 km/s, which is rounded up to 300,000 km/s for convenience.

D. None of the above: This option is incorrect because Option C is the correct answer.

Therefore, the Answer is: C. 300,000 Km/Sec

Multiple choice general knowledge science & technology

Speed of Light in Vaccum?

  1. 3*10^10 m/s

  2. 3*10^10 cm/s

  3. 3*10^8 km/s

  4. 3*10^8 cm/s
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The speed of light in vacuum is approximately 3×10^8 m/s, which equals 3×10^10 cm/s. Option B correctly converts this value to centimeters per second, while the other options use incorrect units or magnitudes.

Multiple choice general knowledge science & technology

which type of electromagnetic waves has slightly longer wavelengths than redlight

  1. yellow

  2. infrared

  3. green

  4. ultraviolet
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Infrared waves have longer wavelengths than visible red light. The visible spectrum ranges from approximately 380nm (violet) to 750nm (red). Infrared radiation starts just beyond red light (~700nm-1mm) and has longer wavelengths. Yellow and green have shorter wavelengths than red (~570-590nm for yellow, ~495-570nm for green), while ultraviolet has shorter wavelengths than the entire visible spectrum (~10-400nm).

Multiple choice general knowledge science & technology

What is the wavelength interval of Blue color?

  1. 490–450 nm

  2. 560–490 nm

  3. 700–630 nm

  4. 450–400 nm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Blue light in the visible spectrum has a wavelength range of approximately 450-495 nanometers. The option '490-450 nm' represents this range, though it's written in descending order. This wavelength range places blue light between green (longer wavelengths) and violet (shorter wavelengths) in the electromagnetic spectrum. Blue light has higher frequency and energy compared to green and yellow light.

Multiple choice general knowledge science & technology

Light year is related to

  1. Energy

  2. Speed

  3. Distance

  4. Intensity
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A light year is a unit of distance equal to the distance light travels in one year (about 5.88 trillion miles or 9.46 trillion kilometers). It is not a measure of energy, speed, or intensity.

Multiple choice general knowledge science & technology

Light year is related to

  1. Energy

  2. Speed

  3. Distance

  4. Intensity
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A light year is a unit of distance, not time. It measures the distance light travels in one year, approximately 9.46 trillion kilometers or 5.88 trillion miles. Astronomers use this unit to measure vast interstellar and intergalactic distances.

Multiple choice general knowledge

Light year is related to

  1. Energy

  2. Speed

  3. Distance

  4. Intensity
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A light year is a unit of distance, not time. It measures how far light travels in vacuum in one year (about 9.46 trillion kilometers or 5.88 trillion miles). Astronomers use it to measure vast distances between stars and galaxies.

Multiple choice general knowledge science & technology

Dark lina in the spectrum is showing

  1. Fraunhofer lines

  2. FitzGerald lines

  3. Hertzprung lines

  4. Bosch lines
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Fraunhofer lines are dark absorption lines in the solar spectrum, caused by elements in the Sun's outer atmosphere absorbing specific wavelengths. They were first systematically studied by Joseph von Fraunhofer in 1814. The other named scientists contributed to other areas of physics.

Multiple choice general knowledge science & technology

What is the speed of light?

  1. 3 x 10^8 m/s

  2. 3 x 10^9 m/s

  3. 3 x 10^10 m/s

  4. 3 x 10^11 m/s
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The speed of light in vacuum is approximately 3 × 10^8 meters per second, a fundamental constant in physics. This value is denoted by 'c' and is the maximum speed at which all massless particles and waves can travel. The other options (10^9, 10^10, 10^11) are orders of magnitude too large. This constant is crucial in relativity and many areas of modern physics.