Stopping Potential And Maximum Kinetic Energy

Question

During a photoelectric experiment the reverse voltage at which the photocurrent just becomes zero is recorded as $1.5\ 	ext{V}$. What is the maximum kinetic energy of the emitted photoelectrons in electron-volts?

RankGuru · Accepted Answer

The stopping potential $V_0$ is the minimum negative voltage on the collector that turns back even the fastest photoelectrons, reducing the photocurrent to zero. At this point the work done by the retarding field on an electron exactly equals the electron's maximum kinetic energy, so $eV_0=K_{max}$. Expressed in electron-volts, the maximum kinetic energy is numerically equal to the stopping potential in volts, because one electron-volt is by definition the energy gained by one electronic charge moving through one volt. Hence $K_{max}=1.5\ 	ext{eV}$. The value $3.0\ 	ext{eV}$ wrongly doubles the result. The value $0.75\ 	ext{eV}$ halves it. The value $2.4	imes10^{-19}\ 	ext{eV}$ confuses joules with electron-volts, since $1.5\ 	ext{eV}=2.4	imes10^{-19}\ 	ext{J}$, not eV. This direct correspondence between stopping potential and electron energy is a cornerstone of the photoelectric measurements described in NCERT. As a unit check, the eV scale keeps numbers convenient and confirms the answer's consistency.

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Stopping Potential And Maximum Kinetic Energy

Select the correct option:

🔒 Solution Hidden from View

More dual nature of radiation and matter Practice Questions

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About This Question

Solution

In a photoelectric experiment the stopping potential rises from $0.50 V$ to $2.15 V$ ...

Inside a reactor a neutron of mass $1.67 \times 1 0^{- 27} kg$ has been slowed to thermal equili...

Identical electrons are accelerated from rest, one through a potential difference of $50 V$ ...

A metal surface of work function $1.0 eV$ is illuminated separately by light of wavelength $...

A photoemissive metal requires a minimum energy of $3.3 eV$ to release an electron from its ...

Monochromatic radiation of wavelength $248 nm$ falls on a photosensitive cathode whose work ...

Green light of wavelength $5 \times 1 0^{- 7} m$ from a laser pointer is incident normally on a ...

A small laser diode of output power $2 mW$ emits a steady beam of monochromatic red light of...