CLASS 12 ELECTROMAGNETIC WAVE IMPORTANT QUESTION 100 % WILL COME IN CBSE
1.To which part of the
electromagnetic spectrum does a wave of frequency 5 x 1019 Hz
belong?
2.To which part of the
electromagnetic spectrum does a wave of frequency 3 x 1013 Hz
belong?
3.Write the condition under which an electron will move undeflected in
the presence of crossed electric and magnetic fields.
4.Welders wear special goggles or face masks with glass windows to protect
their eyes from electromagnetic radiation. Name the radiations and write the
range of their frequency.
5.What are the directions of electric and magnetic field vectors relative to
each other and relative to the direction of propagation of electromagnetic
waves?
6.Name the electromagnetic waves which
(i) maintain the earth’s warmth and
(ii) are used in aircraft navigation.
7.A plane electromagnetic wave travels in vacuum along Z- direction. What
can you say about the direction of electric and magnetic field vectors?
8.Write two uses of microwaves.
9. Write two uses of infrared rays.
10.Write two uses of X-rays.
11.What is the frequency of electromagnetic waves produced by
oscillating charge of frequency V=105Hz?
12.How are infrared waves produced? What is the range of their
wavelength?
13.Which of the following has the shortest wavelength? Microwaves,
ultraviolet rays, X-rays.
14. Arrange the following in descending order of wavelength. X-rays,
radiowaves, blue light, infrared light.
15. Which part of electromagnetic spectrum has largest penetrating
power?
16. Which part of electromagnetic spectrum is absorbed from sunlight by
ozone layer?
17. Which part of electromagnetic spectrum is used in RADAR
systems?
18.Name the electromagnetic radiation
used to destroy cancer cells and write its frequency range.
19.In what way, are the directions of the electric and magnetic field
vectors representing an electromagnetic wave related to each
other?
20.Express the velocity of propagation of an electromagnetic waves in terms
of the peak value of the electric and magnetic fields.
21.Name the
electromagnetic waves used for studying crystal structure of solids. What is
its frequency range?
22.Write the following radiations in ascending order in respect of their
frequencies X-rays, microwaves, ultraviolet rays and radiowaves.
23.Name the electromagnetic radiation to which waves of wavelength in the
range of 10-2 m belongs. Give one use of this part of
electromagnetic spectrum.
24.Name the electromagnetic radiation which can be produced by a
klystron or a magnetron valve.
25.Why is ozone layer
on top of the stratosphere crucial for human survival?
26.State the reason why microwaves are best suited for long distance
transmission of signals.
27.Special devices like the klystron valve or the magnetron valve, are
used for production of electromagnetic waves. Name these waves and also write
one of their
applications.
2 Marks Questions
28.(a) How does
oscillating charge produce electromagnetic waves?
(b) Sketch a schematic diagram depicting oscillating electric and magnetic
fields of an EM wave propagating along positive Z-direction.
29.(i) How are electromagnetic waves produced?
(ii) How do you convince yourself that electromagnetic waves carry energy
and momentum?
30.(i) Arrange the following electromagnetic waves in the descending
order of their wavelengths.
·
Microwaves
·
Infrared
rays
·
Ultraviolet
radiation
·
y-rays
(ii) Write one use
each of any two of them.
31.(i) An electromagnetic wave is travelling in a medium, with a
velocity v = vi. Draw a sketch showing the propagation of the electromagnetic
wave, indicating the direction of the oscillating electric and magnetic fields.
(ii) How are the magnitudes of the electric and magnetic fields related to
velocity of the electromagnetic wave? [HOTS;
32.A capacitor of
capacitance C is being charged by connecting it across a DC source along
with an ammeter. Will the ammeter show a momentary deflection during the
process of charging? If so, how would you explain this momentary
deflection and the resulting continuity of current in the circuit? Write the
expression for the current inside the capacitor.
33.When an ideal
capacitor is charged by a DC battery, no current flows. However, when an AC
source is used, the current flows continuously. How does one explain this,
based on the concept of displacement current?
34.Explain briefly how
electromagnetic waves are produced by an oscillating charge? How is the
frequency of the electromagnetic waves produced related to that of the
oscillating charge?
35.Name the constituent radiation of electromagnetic spectrum which is used
for
·
aircraft
navigation
·
studying
the crystal structure Write the frequency range for each.
36.Draw a sketch of a plane electromagnetic wave propagating along the
Z-direction. Depict clearly the directions of electric and magnetic fields
varying sinusoidally with Z.
37.Arrange the
following electromagnetic radiations in ascending order of their frequencies.
·
Microwaves
·
Radio
waves
·
X-rays
·
y-rays
Write two uses of any
one of these.
38.How are X-rays produced? Write their two important uses.
39.How are infrared rays produced? Write their two important uses.
40.How are microwaves
produced? Write their two important uses.
41.Answer the following questions.
·
Optical
and radio telescopes are built on the ground while X-ray astronomy is possible
only from satellites orbiting the earth. Why?
·
The
small ozone layer on top of the stratosphere is crucial for human
survival. Why?
42.How does a charge, q oscillating at certain frequency produce
electromagnetic waves? Sketch a schematic diagram depicting electric and
magnetic fields for an electromagnetic wave propagating along the Z- direction.
43.Name the electromagnetic radiations having the wavelength range from 1 mm
to 700 nm. Give its two important applications.
44.Name the electromagnetic radiation having the wavelength range from 10-1 m
to 10~3 Give its two important applications.
45.Name the electromagnetic radiations having the wavelength range from 1 nm
to 10~3 Give its two important applications.
·
46.Identify
the different types of electromagnetic radiations, which are used
·
to
kill germs,
·
for
physical therapy.
47.In an electromagnetic wave, the oscillating electric field having a
frequency of 3 x 1010 Hz and an amplitude of 30 V/m propagates
in the positive X-direction.
·
What
is the wavelength of the electromagnetic wave?
·
Write
down the expression to represent the corresponding magnetic
field.
48.The following table gives the wavelength range of some constituents of
the electromagnetic spectrum.
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