Photoelectric emission occurs only when the incident light has more than a certain minimum

Options

A. wavelength
B. intensity
C. frequency
D. power

Answer

To solve the question regarding photoelectric emission, we will follow these steps:

### Step 1: Understand the Photoelectric Effect
The photoelectric effect is the phenomenon where electrons are emitted from a material (usually a metal) when it is exposed to light of sufficient frequency. This effect is explained by Einstein’s photoelectric equation.

### Step 2: Write the Photoelectric Equation
Einstein's photoelectric equation is given by:
\[ KE_{\text{max}} = h\nu - h\nu_0 \]
Where:
- \( KE_{\text{max}} \) is the maximum kinetic energy of the emitted electrons.
- \( h \) is Planck's constant.
- \( \nu \) is the frequency of the incident light.
- \( \nu_0 \) is the threshold frequency (minimum frequency required for photoelectric emission).

### Step 3: Determine the Condition for Emission
For photoelectric emission to occur, the maximum kinetic energy must be greater than zero:
\[ KE_{\text{max}} > 0 \]
This leads to the condition:
\[ h\nu - h\nu_0 > 0 \]
Simplifying this, we find:
\[ h\nu > h\nu_0 \]
Dividing by \( h \) (since \( h \) is a positive constant):
\[ \nu > \nu_0 \]

### Step 4: Identify the Minimum Frequency
The minimum frequency \( \nu_0 \) is known as the threshold frequency. It is the frequency below which no photoelectric emission occurs, regardless of the intensity of the light.

### Step 5: Conclusion
Thus, we conclude that photoelectric emission occurs only when the incident light has a frequency greater than the threshold frequency \( \nu_0 \).

### Final Answer
Photoelectric emission occurs only when the incident light has more than a certain minimum frequency, known as the threshold frequency.

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