At threshold: hc/λ₀ = φ. So λ₀ = hc/φ = 1240/4.2 ≈ 295 nm
JEE Main 2023 — Physics Modern Physics
The work function of a metal is 4.2 eV. The threshold wavelength is (hc = 1240 eV·nm):
Verified 30 May 2026.
295 nm
300 nm
310 nm
325 nm
Sign in to track your attempts and accuracy.
Sign in to keep a private note on this question. Nothing you write is ever public.
Two $4$ bits binary numbers, $A = 1101$ and $B = 1010$ are given in the inputs of a logic circuit shown in figure below. The output $(Y)$ will be: 
Two radioactive substances A and B of mass numbers $200$ and $212$ respectively, shows spontaneous $\alpha$-decay with same $Q$ value of $1$ MeV. The ratio of energies of $\alpha$-rays produced by A and B is ________.
Using Bohr's model, calculate the ratio of the magnetic fields generated due to the motion of the electrons in the $2^{\text{nd}}$ and $4^{\text{th}}$ orbits of hydrogen atom _______.
The de Broglie wavelength for an electron accelerated through the potential difference of $V_1$ volt is $\lambda_1$. When the potential difference is changed to $V_2$ volt, the associated de Broglie wavelength is increased by $50\%$. If $(V_1/V_2) = (9/\alpha)$, then the value of $\alpha$ is __________.
The output $Y$ for the given inputs $A$ and $B$ to the circuit is: 
Work through every JEE Main Modern Physics PYQ, year by year.