Question:
If an electromagnetic wave of frequency \(5\) MHz travels from vacuum into a dielectric medium of electric permittivity \(\varepsilon_r=4\), then its
If an electromagnetic wave of frequency \(5\) MHz travels from vacuum into a dielectric medium of electric permittivity \(\varepsilon_r=4\), then its
Show Hint
When a wave enters a new medium, frequency stays constant. Speed and wavelength change together.
Updated On: Apr 29, 2026
- wavelength is halved and frequency remains unchanged
- wavelength and frequency are both doubled
- wavelength and frequency both remain unchanged
- wavelength is doubled but the frequency remains unchanged
- wavelength remains unchanged but the frequency is doubled
Show Solution
Verified By Collegedunia
The Correct Option is A
Solution and Explanation
In a dielectric medium:
\[
v=\frac{c}{\sqrt{\varepsilon_r}}
=\frac{c}{\sqrt{4}}
=\frac{c}{2}
\]
Frequency remains unchanged when a wave enters another medium.
Since
\[
\lambda=\frac{v}{f}
\]
if speed becomes half and \(f\) stays same, wavelength becomes half.
Hence,
\[
\boxed{(A)\ \text{wavelength is halved and frequency remains unchanged}}
\]
Was this answer helpful?
0
0
Top KEAM Physics Questions
- A body oscillates with SHM according to the equation (in SI units), $x = 5 cos \left(2\pi t +\frac{\pi}{4}\right) .$ Its instantaneous displacement at $t = 1$ second is
Kepler's second law (law of areas) of planetary motion leads to law of conservation of
- Two capillary tubes A and B of diameter $1\, mm$ and $2\, mm$ respectively are dipped vertically in a liquid. If the capillary rise in A is 6 cm, then the capillary rise in B is
- In the circuit given in figure, 1 and 2 are ammeters. Just after key K is pressed to complete the circuit, the reading will be
- A plate has a length $ 5\pm 0.1\text{ }cm $ and breadth $ 2\pm 0.01\text{ }cm $ . Then the area of the plate is:
View More Questions
Top KEAM Electromagnetic Spectrum Questions
- The correct order of arrangement of electromagnetic waves according to their wavelengths is
- Electromagnetic waves of frequency \( 5 \times 10^{14} \, {Hz} \) lie in the
- If work function of a metal is 6.6 eV, find the threshold wavelength. \text{Given} \( h = 6.6 \times 10^{-34} \, \text{J} \cdot \text{s} \).
- If \( v_g, v_X \) and \( v_v \) are the speeds of gamma rays, X-rays and visible light respectively in vacuum, then
- The electromagnetic waves used in radar systems for aircraft navigation are
View More Questions
Top KEAM Questions
- i.$\quad$ They help in respiration ii.$\quad$ They help in cell wall formation iii.$\quad$ They help in DNA replication iv. $\quad$They increase surface area of plasma membrane Which of the following prokaryotic structures has all the above roles?
- A body oscillates with SHM according to the equation (in SI units), $x = 5 cos \left(2\pi t +\frac{\pi}{4}\right) .$ Its instantaneous displacement at $t = 1$ second is
- The pH of a solution obtained by mixing 60 mL of 0.1 M BaOH solution at 40m of 0.15m HCI solution is
Kepler's second law (law of areas) of planetary motion leads to law of conservation of
- If $\int e^{2x}f' \left(x\right)dx =g \left(x\right)$, then $ \int\left(e^{2x}f\left(x\right) + e^{2x} f' \left(x\right)\right)dx =$
View More Questions