1
JEE Main 2020 (Online) 5th September Morning Slot
Numerical
+4
-0
Out of Syllabus
A beam of electrons of energy E scatters from a target having atomic spacing of 1 $$\mathop A\limits^o$$. The first maximum intensity occurs at $$\theta$$ = 60o. Then E (in eV) is ______.
(Planck constant h = 6.64 × 10–34 Js,
1 eV = 1.6 × 10–19 J, electron
mass m = 9.1 × 10–31 kg)
2
JEE Main 2020 (Online) 2nd September Morning Slot
Numerical
+4
-0
When radiation of wavelength $$\lambda$$ is used to illuminate a metallic surface, the stopping potential is V. When the same surface is illuminated with radiation of wavelength 3$$\lambda$$, the stopping potential is $${V \over 4}$$. If the threshold wavelength for the metallic surface is n$$\lambda$$ then value of n will be __________.
3
JEE Main 2020 (Online) 7th January Morning Slot
Numerical
+4
-0
A beam of electromagnetic radiation of intensity 6.4 × 10–5 W/cm2 is comprised of wavelength, $$\lambda$$ = 310 nm. It falls normally on a metal (work function $$\phi$$ = 2eV) of surface area of 1 cm2. If one in 103 photons ejects an elctron, total number of electrons ejected in 1 s is 10x. (hc = 1240 eVnm, 1eV = 1.6 × 10–19 J), then x is _____.