In a medium the speed of light wave decreases to 0.2 times to its speed in free space. The ratio of relative permittivity to the refractive index of the medium is x:1. The value of x is ______.
(Given speed of light in free space =3×108ms−1 and for the given medium μr=1)
Held on 31 Jan 2023 · Verified 6 Jul 2026.
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Which of the following are true for a single slit diffraction? A. Width of central maxima increases with increase in wavelength keeping slit width constant. B. Width of central maxima increases with decrease in wavelength keeping slit width constant. C. Width of central maxima increases with decrease in slit width at constant wavelength. D. Width of central maxima increases with increase in slit width at constant wavelength. E. Brightness of central maxima increases for decrease in wavelength at constant slit width.
In parallax method for the determination of focal length of a concave mirror, the object should always be placed:
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Work through every JEE Main Optics PYQ, year by year.