Question:
If the wavelength of the incident radiation on a photosensitive metal surface is decreased from \(3100 \, \text{Å}\) to \(1550 \, \text{Å}\), the maximum kinetic energy of the emitted photoelectrons is tripled.
- The work function of the metal surface is
If the wavelength of the incident radiation on a photosensitive metal surface is decreased from \(3100 \, \text{Å}\) to \(1550 \, \text{Å}\), the maximum kinetic energy of the emitted photoelectrons is tripled.
- The work function of the metal surface is
Show Hint
For photoelectric effect problems, use Einstein’s equation:
\[
h f = \phi + K_{\text{max}}
\]
where \( E = \frac{hc}{\lambda} \). Ensure wavelengths are converted to consistent units.
Updated On: May 5, 2026
- \(3 \, eV\)
- \(4 \, eV\)
- \(2 \, eV\)
- \(6 \, eV\)
Show Solution
Verified By Collegedunia
The Correct Option is C
Solution and Explanation
Step 1: Einstein’s Photoelectric Equation
\[ hf = \phi + K_{\max} \]
Photon energy:
\[ E = \frac{hc}{\lambda}, \quad hc = 12400 \, \text{eV·\AA} \]
Step 2: Calculate photon energies
For \( \lambda_1 = 3100 \, \text{\AA} \):
\[ E_1 = \frac{12400}{3100} = 4 \, \text{eV} \]
For \( \lambda_2 = 1550 \, \text{\AA} \):
\[ E_2 = \frac{12400}{1550} = 8 \, \text{eV} \]
Step 3: Apply given condition
\[ E_1 = \phi + K_1 \] \[ E_2 = \phi + 3K_1 \]
Subtracting:
\[ E_2 - E_1 = 2K_1 \]
\[ 8 - 4 = 2K_1 \Rightarrow K_1 = 2 \, \text{eV} \]
Step 4: Find work function
\[ \phi = E_1 - K_1 = 4 - 2 = 2 \, \text{eV} \]
Final Answer: \( 2 \, \text{eV} \)
Was this answer helpful?
0
0
Top TS EAMCET Physics Questions
- A wooden box lying at rest on an inclined surface of a wet wood is held at static equilibrium by a constant force $F$ applied perpendicular to the incline. If the mass of the box is $1\,kg$, the angle of inclination is $30^{\circ}$ and the coefficient of static friction between the box and the inclined plane is $0.2$, the minimum magnitude of $\vec{F}$ is (Use $ g = 10\,m/s^2$)
- A metre scale made of steel reads accurately at $25^{\circ} C$ . Suppose in an experiment an accuracy of $0.06\, mm$ in $1\,m$ is required, the range of temperature in which the experiment can be performed with this metre scale is (coefficient of linear expansion of steel is $ 11 \times 10^{-6} /^{\circ} \, C$ )
- Consider a solenoid carrying current supplied by a DC source with a constant emf containing iron core inside it. When the core is pulled out of the solenoid, the change in current will
- A parallel beam of light of intensity \(I_0\) is incident on a coated glass plate. If \(25\%\) of the incident light is reflected from the upper surface and \(50\%\) of light is reflected from the lower surface of the glass plate, the ratio of maximum to minimum intensity in the interference region of the reflected light is
- A thermocol box has a total wall area (including the lid) of $1.0 m ^{2}$ and wall thickness of $3 cm$. It is filled with ice at $0^{\circ} C$. If the average temperature outside the box is $30^{\circ} C$ throughout the day, the amount of ice that melts in one day is [Use $K_{\text {thermocol }}=0.03 W / mK$ $.L_{\text {fusion (ice) }}=3.00 \times 10^{5} J / kg ]$
View More Questions
Top TS EAMCET Magnetic Force Questions
- An electron moves in a combined electric and magnetic field, the electric field being $1.5 \times 10^3 \, V/m$ and magnetic field being 0.75 T. If the resultant force on the moving electron is to be zero, the minimum velocity of the electron in km s is
- A current \( i \) flows through a circular loop of radius \( R \). The ratio of the magnetic field produced at its centre to the field produced at a point at a distance \( \frac{R}{\sqrt{3}} \) from its centre on its axis is:
- Two particles of charges in the ratio \( 1:2 \) and masses in the ratio \( 2:3 \) moving along a straight line enter a uniform magnetic field at right angles to the direction of the field. If the radii of the circular paths of the particles in the magnetic field are in the ratio \( 3:4 \), then the ratio of the initial linear momenta of the two particles is:
- Magnetic field on the axis of a short bar magnet of magnetic moment \( M \), at a distance \( x \) from its centre is:
- The self-induced emf of a coil is 36 V. If the current in the coil is changed from 12 A to 24 A in one second, then the change in the energy stored in the coil is:
View More Questions
Top TS EAMCET Questions
- A bag contains $5$ red balls, $3$ black balls and $4$ white balls are drawn at random. The probability that they are not of same colour is
- If $cosec\, \theta - \cot \theta = 2017$, then quadrant in which $\theta $ lies is
- If $a$ is a unit vector, then $| a \times \hat{ i }|^{2}+| a \times \hat{ j }|^{2}+| a \times \hat{ k }|^{2}=$
- $A$ straight line makes an intercept on the $Y$-axis twice as long as that on $X$-axis and is at a unit distance from the origin. Then the line is represented by the equations
- Let $S$ and $S'$ be the foci of an ellipse and B be one end of its minor axis. If $SBS'$ is an isosceles right angled triangle then the eccentricity of the ellipse is
View More Questions