Physics Chemistry & Biology Test 2
Radio waves are
  • Electromagnetic waves
  • Mechanical waves
  • Magnetic Waves
Explanation:

Radio waves are electromagnetic waves. They are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum ranging from about one millimeter to 100 kilometers, and they are used in various communication technologies, including radio, television, and wireless networks.

Units of focal power
  • cm
  • Dioptre
  • mtrs
Explanation:

The unit of focal power is Dioptre. It is defined as the reciprocal of the focal length measured in meters. A lens with a focal length of 1 meter has a focal power of 1 dioptre.

Bending of light rays around the smaller obstacles is called
  • Refraction
  • Di fraction
  • Reflection
Explanation:

The bending of light rays around smaller obstacles is called Di fraction. Diffraction occurs when light encounters an obstacle or a slit that is comparable in size to its wavelength, causing the light to spread out and bend around the edges.

Sun glasses works on the principle
  • Polarization of light
  • Diffraction of light
  • Refraction of light
Explanation:

Sunglasses work on the principle of polarization of light.

They are designed to reduce glare from surfaces like water or roads by blocking certain orientations of light waves, which helps improve visibility and reduce eye strain.

Magnitude of diffraction of light is depends on
  • Size of the obstacle
  • Wave length of the light wave
  • Angle of beam of the light ray
  • All of the above
Explanation:

The magnitude of diffraction of light depends on all the above factors:

  1. Size of the obstacle: Smaller obstacles relative to the wavelength of light cause more significant diffraction.
  2. Wavelength of the light wave: Longer wavelengths diffract more than shorter wavelengths.
  3. Angle of the beam of the light ray: The angle at which light strikes an obstacle can also influence the diffraction pattern.

Therefore, all these factors play a role in the diffraction of light.

Which rays are used to night vision
  • X rays
  • gamma rays
  • Infrared rays
Explanation:

Infrared rays are used for night vision. Night vision devices often utilize infrared technology to detect heat emitted by objects, allowing them to create images in low-light or dark conditions. X-rays and gamma rays are not typically used for night vision applications.

To detect fake notes, we use
  • X rays
  • Explanation:

    To detect fake notes, we use UV rays (ultraviolet rays). Many currencies have features that are only visible under UV light, such as watermarks and security threads, which help in identifying counterfeit bills.