Photoelectric Effect

Step 1: Concept
Einstein's photoelectric equation: .
Step 2: Analysis
Energy of photon .
.
Step 3: Conclusion
.
Final Answer: (A)

Step 1: Identification
The configuration belongs to Sodium ( , ).
Step 2: Classification
Sodium is an alkali metal (Group 1).
Step 3: Property
Oxides of highly electropositive metals, especially alkali metals, are strongly basic in nature.
Step 4: Conclusion
Thus, the oxide ( ) is basic.
Final Answer: (c)

Concept:

Step 1: New wavelength smaller energy increases

Step 2: Since constant, increase in KE is more than linear

Concept:

Step 1: Energy per photon

Step 2: Power entering eye

Step 3: Number of photons

Step 1: Understanding the Concept:
The photoelectric effect is the emission of electrons from a metal surface when light falls on it. The ease of emission depends on the work function (ionization energy) of the metal.

Step 2: Detailed Explanation:
The photoelectric effect is more pronounced for metals with low work functions (low ionization energies). Ionization energy decreases down the alkali metal group. Cesium (Cs) has the lowest ionization energy among the given options (Li, Na, K, Cs). Therefore, it exhibits the maximum photoelectric effect.

Step 3: Final Answer:
Cesium (Cs) has the maximum photoelectric effect, which corresponds to option (D).

Concept: Photoelectric effect condition: Since , this implies:

Step 1: Relation between wavelength and frequency.
Higher frequency lower wavelength.

Step 2: Conclusion.

Concept: Stopping potential is related to maximum kinetic energy:

Step 1: Given data.


Step 2: Relation.


Step 3: Sign convention.
Stopping potential is negative (retarding potential).

Concept: Photoelectric equation: Stopping potential:

Step 1: Find wavelength.
Comparing with standard wave equation :

Step 2: Photon energy.


Step 3: Maximum kinetic energy.


Step 4: Stopping potential.
Since :

Concept: Energy of photon:

Step 1: Energy depends only on frequency:

Step 2: Intensity affects number of electrons emitted, not their energy.

Step 3: Thus:
•(A) Correct
•(B) Wrong (independent of intensity)
•(C) Wrong (KE depends on frequency)
•(D) Incorrect statement

Concept:
•Photoelectric equation:
•Motion in magnetic field:
•Kinetic energy:

Step 1: Given data

Step 2: Kinetic energy (in eV)

Step 3: Photon energy

Step 4: Work function Final: 4.5 eV

Concept: Photoelectric equation:

Step 1:Initial stopping potential

Step 2:When frequency is doubled

Step 3:Compare with

Step 4:Compare and Conclusion