TG EAMCET 2 May 2025 Shift 2 Paper

When light hits a photosensitive material, electrons are released. The energy of the incoming light (photon) is used to release these electrons and provide them with some extra energy.
Einstein's photoelectric equation helps us understand this process:
Emax=hν−φ0
This means: the maximum energy of the emitted electrons equals the energy of the incoming photon minus the work function (φ0), which is the energy needed to release the electron.
The stopping potential ( V0 ) is linked to this energy by:
eV0=hν−φ0
or
V0=‌

hν

e

−‌

φ0

e

First, use the given values for the first case:
For photon energy 3.1 eV and stopping potential 1.7 V :
‌V0=3.1−‌

φ0

e

‌1.7=3.1−‌

φ0

e

To find the work function divided by e :
‌

φ0

e

=3.1−1.7=1.4
So, ‌

φ0

e

=1.4 volt
Now, use this value for the second case:
For photon energy 2.5 eV :
‌V0=2.5−‌

φ0

e

‌V0=2.5−1.4=1.1V