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Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

Which one of waves cannot be seen through electromagnetic spectrum?

  1. radio waves

  2. micro waves.

  3. infrared waves.

  4. ultraviolet waves.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Red, blue, green, yellow, orange colors are all part of electromagnetic spectrum that are visible to human eye.
The part which is not visible are UV, X-RAY, GAMMA RAY which have lower wavelength than visible light and infrared, radio waves have higher wavelength than visible.
Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

To distinguish between real gems and artificial gems a merchant may use which of the following radiations?

  1. Infrared rays
  2. $\gamma$-rays

  3. X-rays

  4. Ultraviolet rays
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

To distinguish between real gems and artificial gems a merchant may use infrared radiations. A number of synthetic gems can be distinguished from their natural counterparts by differences in their infrared spectra.  

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

Maximum diffraction takes place in a given slit for

  1. $\gamma $-rays

  2. Ultraviolet light

  3. Infrared light

  4. Radio waves
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
When the gap size is larger than the wavelength, the wave passes through the gap and does not spread out much on the other side. When the gap size is equal to the wavelength, maximum diffraction occurs. So among all of them radio waves have minimum wavelength and hence it will give maximum diffraction. 
Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

The frequencies of X-rays, $\gamma-rays$ and ultra violet rays are respectively $p, q$ and $r$, then

  1. $p > q, q > r$
  2. $p < q, q > r$
  3. $p < q, q < r$
  4. $p > q, q < r$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Increasing order of wavelengths as given below
$\gamma-rays < X-rays >$ ultravoilet rays
Frequency order
$\gamma-ray > X-rays >$ ultravoilet rays
$\Rightarrow q > p > r$
Thus, $q > p$
$q > r$
$p > r$.

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

What name is given to the type of astronomy having the following characteristics.
I. It is carried out in the waveband $300$nm to $10$nm.
II. The atmosphere is opaque to the incoming radiation from space
III. Observations are to be carried out from above the earth's atmosphere.

  1. X-ray astronomy

  2. Ultra-violet astronomy

  3. Infra-red astronomy

  4. Gamma ray astronomy
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Ultra-violet astronomy is carried out in waveband of $10nm-300nm$ in which is above earth's atmosphere.
Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

A beam of ultraviolet light of all wavelengths passes through hydrogen gas at room temperature, in the $x-$direction. Assume that all photons emitted due to electron transitions inside the gas emerge in the $y-$direction. Let $A$ and $B$ denote the lights emerging from the gas in the $x-$ and $y-$directions respectively. Then,

  1. some of the incident wavelengths will be absent in $A$
  2. only those wavelengths will be present in $B$ which are absent in $A$
  3. $B$ will contain some visible light
  4. $B$ will contain some infrared light
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

$A, C, D$

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

The magnetic field in a plane electromagnetic wave is given by $=2\times10^{-7} \sin(0.5\times 10^3 x+1.5\times10^{11}t)$. This electromagnetic wave is

  1. Visible light

  2. Infrared

  3. Microwave

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

The magnetic field in a plane of electromagnetic  wave is given by

$B=2\times 10^{-7}sin(0.5\times 10^3x+1.5\times 10^{11}t)$
from the above, $K=0.5\times 10^3=$ propagation constant
$K=\dfrac{2\pi}{\lambda}$ where, $\lambda=$ wavelength of wave
$\lambda=\dfrac{2\times 3.14}{0.3\times 10^3}$
$\lambda=1.256\times 10^{-2}m$
$\lambda=1.256 cm$
The electromagnetic wave is Microwave radiation in spectrum.

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

In the EM wave , the amplitude of magnetic field $ H _o $ and the amplitude of electric field $ E _o $ at a place D are related as:

  1. $ H _o = E _o $
  2. $ H _ o=\frac { E _ o }{ c } $
  3. $ H _ o=\quad E _ o\quad \sqrt { \frac { \mu _ o }{ \varepsilon _ o } } $
  4. $ H _ o=\quad E _ o\quad \sqrt { \frac { \varepsilon _ o }{ \mu _ o } } $
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In an electromagnetic wave, the relationship between the amplitudes of the electric field E0 and the magnetic field H0 is H0 = E0 * sqrt(epsilon / mu).