Download App

Electromagnetic Waves — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsElectromagnetic Waves3 Marks
Question
  1. Which segment of electromagnetic waves has highest frequency? How are these waves produced ? Give one use of these waves.
  2. Which em waves lie near the high-frequency end of visible part of em spectrum? Give its one use. In what way this component of light has harmful effects on humans?
✓

Answer

  1. $\gamma\text{ }\text{rays}.$
Produced in nuclear reactions and emitted by radioactive decay of nucleus.
Used in medicine to destroy cancer cells.
  1. Ultra violet rays
Used in LASIK eye surgery, UV lamps to kill germs in water purifier.
Causes sunburn/skin cancer/harms eyes when exposed to direct UV rays.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Electromagnetic Waves→Electromagnetic Waves — all question types→Physics STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

A horizontal straight wire $10m$ long extending from east to west is falling with a speed of $5.0\ ms^{–1},$ at right angles to the horizontal component of the earth’s magnetic field, $0.30 \times 10^{–4}Wbm^{–2}.$
  1. What is the instantaneous value of the emf induced in the wire?
  2. What is the direction of the emf?
  3. Which end of the wire is at the higher electrical potential?
​​​​​​​
→
We have valence electrons and conduction electrons in a semiconductor. Do we also have 'valence holes' and 'conduction holes'?
→
A particle starts from the origin, goes along the X-axis to the point (20m, 0) and then returns along the same line to the point (-20m, 0). Find the distance and displacement of the particle during the trip.
→
Radiation from hydrogen discharge tube falls on a cesium plate. Find the maximum possible kinetic energy of the photoelectrons. Work function of cesium is 1.9eV.
→
  1. Name the waves which are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves.
  2. If the earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain.
  3. An wave exerts pressure on the surface on which it is incident. Justify.
→
Concentric equipotential surfaces due to a charged body placed at the centre are shown. Identify the polarity of the charge and draw the electric field lines due to it.
→
Photoelectrons are emitted from a metal surface when illuminated with $UV$ light of wavelength $330 nm$ . The minimum amount of energy required to emit the electrons from the surface is $3.5 \times 10^{-19} J$. Calculate :
$a$. the energy of the incident radiation, and
$b$. the kinetic energy of the photoelectron.
→
Does a nucleus lose mass when it suffers gamma decay?
→
Given a uniformly charged plane/sheet of surface charge density, $\sigma=2\times10^{17}\text{C/m}^2.$Image
  1. Find the electric field intensity at a point A, 5mm away from the sheet on the left side.
  2. Given a straight line with three points X, Y and Z placed 50cm away from the charged sheet on the right side. At which of these points, the field due to the sheet remain the same as that of point A and why?
→
A point source emitting light uniformly in all directions is placed 60cm above a table-top. The illuminance at a point on the table-top, directly below the source, is 15 lux. Find the illuminance at a point on the table-top 80cm away from the first point.
→