ICS Part 1 Physics English Medium Chapter 10 Online Short Questions Test with Answers

What is spectrometer?

• Ans 1: Spectrometer is a device which is used to study the spectra from different light sources.
  Its main parts are
  1. Collimator
  2. Turntable
  3. Telescope

  
  

If the person was looking through a telescope at thee full moon, how would the appearance of the moon be changed by covering half of the objective lens?

• Ans 1: How will see the full moon still but the brightness will be reduced because less light is transmitting through the half covered lens.

What is the condition for total internal reflection?

• Ans 1: For glass- air boundary , when a propagating wave strikes the boundary at an angle larger than critical angle with respect to the normal to the surface, all the light is reflected and none is refracted to the air. This phenomenon is called total internal reflection. When a light ray travelling from a denser medium towards a rare medium, makes an angle of incidence greater than critical angle of the medium, then the ray is totally reflected back into the same denser medium.

When object lie within the principle focus of convex lens what is the nature of image and where it is formed?

• Ans 1: When object lie within the principle focus of convex lens, then image will be virtual, erect and magnified and will be formed at least distance of distinct vision.

Find magnifying power of a convex lens of 25 cm focal length act as a magnifying glass.

• Ans 1:

Write any two uses of spectrometer.

• Ans 1: It is used to study spectra from different sources of light.Its is used to determine the wavelength of light.

What do you mean by "Normal adjustment " in an astronomical telescope?

• Ans 1: In normal adjustment, the image formed by the objective lies at the focus of both the objective and the eye-piece and the final image appears to be formed at infinity. The distance between the objective and eye-piece of a telescope in normal adjustment is f_o+f_{e which equals the length of the telescope.}

A magnifying glass gives a five time enlarged image at a distance of 25 cm from the lens. What will be the focal length of the lens?

• Ans 1:

Why would it be advantageous to use blue light with a compound microscope?

• Ans 1:

What is the function of collimator in a spectrometer?

• Ans 1: Collimator is used to make the light rays parallel. It consists of a fixed metallic tube, a convex lens and an adjustable slit.

Write any two uses of spectrometer.

• Ans 1: It is used to study spectra from different sources of light.Its is used to determine the wavelength of light.

Differentiate between multimode step index and multimode graded index fibre.

• Ans 1:
• Ans 2:

One can buy a cheap microscope for used by the children. The image seen in such a microscope has coloured edges.Why is this so?

• Ans 1: It is due to the defects of lenses known a chromatic aberrations. This is because of the prism like formation of the lens which causes dispersion of white light.

Write the advantages of using light as transmission carrier wave over radio wave carriers.

• Ans 1: The use of light as transmission carrier wave in fibre optics gas several advantages over radio wave carriers such as a much wider bandwidth capability and immunity from electromagnetic interference.

How light signals is transmitted through optical fibre?

• Ans 1: The lights signal are transmitted through the optical on the principle of
  • Total internal reflection
  • Continuous refraction

  In multimedia step index fiber, the signal is transmitted baby means of total internal reflection while in case of multimode graded index fiber, the signals transmitted by total internal reflection and continuous refraction.

Define Magnification.

• Ans 1: The size of the object goes on increasing, when the object brought from a far off point to the focus of the lens. This phenomenon of enlargement is called magnification. Its is the ration of size of image to the size of object.

Why we use infrared light in a fiber optics communication system?

• Ans 1: Infrared light travels faster through optical fiber than visible light. So, it is preferred.

What do you mean by "Normal adjustment " in an astronomical telescope?

• Ans 1: In normal adjustment, the image formed by the objective lies at the focus of both the objective and the eye-piece and the final image appears to be formed at infinity. The distance between the objective and eye-piece of a telescope in normal adjustment is f_o+f_{e which equals the length of the telescope.}

What are different types of optical fibre?

• Ans 1: There are three types of optical fibres.
  1. Single mode step index fibre.
  2. Multimode step index fibre.
  3. Multimode graded index fibre.

What is the function of collimator in a spectrometer?

• Ans 1: Collimator is used to make the light rays parallel. It consists of a fixed metallic tube, a convex lens and an adjustable slit.

Differentiate between multimode step index and multimode graded index fibre.

• Ans 1:
• Ans 2:

Define Snell's law and write its mathematical form.

• Ans 1: Snell's law states that the ratio of the sines of the angles of incidence and refraction of a wave are constant when it passes between two given media. OR Snell' Law is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media such as water, glass, or air.

What are uses of spectrometer?

• Ans 1: It is used to study spectra from different sources of light. Determine the wavelength of light by grating. Study the deviation of light by glass prism.
  Calculate refractive index of prism material

If the person was looking through a telescope at thee full moon, how would the appearance of the moon be changed by covering half of the objective lens?

• Ans 1: How will see the full moon still but the brightness will be reduced because less light is transmitting through the half covered lens.

Focal length of convex lens is 5 cm, calculate its magnification.

• Ans 1:

What are different types of optical fibre?

• Ans 1: There are three types of optical fibres.
  1. Single mode step index fibre.
  2. Multimode step index fibre.
  3. Multimode graded index fibre.

• Ans 1:

Find the magnifying power of a convex lens of 10 cm focal length.

• Ans 1:

Write the advantages of using light as transmission carrier wave over radio wave carriers.

• Ans 1: The use of light as transmission carrier wave in fibre optics gas several advantages over radio wave carriers such as a much wider bandwidth capability and immunity from electromagnetic interference.

Why we use infrared light in a fiber optics communication system?

• Ans 1: Infrared light travels faster through optical fiber than visible light. So, it is preferred.