JEE MAIN - Physics (2025 - 22nd January Morning Shift - No. 8)

The work functions of cesium (Cs) and lithium (Li) metals are 1.9 eV and 2.5 eV , respectively. If we incident a light of wavelength 550 nm on these two metal surfaces, then photo-electric effect is possible for the case of

Both Cs and Li

Neither Cs nor Li

Li only

Cs only

Explanation

For photo-electric effect, energy of the photon must be greater than the work function of the metal.

We know, $$E = {{1240} \over \lambda } = {{1240} \over {550}}$$ (as $\lambda=550$ nm given)

$\Rightarrow E=2.25$ eV

here, $$E > {\phi _{cs}}$$

So, $C_S$ only.

JEE MAIN - Physics (2025 - 22nd January Morning Shift - No. 8)

Explanation

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