A metal surface ejects electrons when hit by green light but none when hit by yellow light. The electrons will be ejected when the surface is hit by

Options

A. blue light
B. heat rays
C. infrared light
D. red light

Explanation

To solve the problem, we need to analyze the relationship between the wavelength of light and the emission of electrons from a metal surface, based on the photoelectric effect.

### Step-by-Step Solution:

1. **Understand the Photoelectric Effect**: The photoelectric effect states that electrons are ejected from a metal surface when it is illuminated by light of sufficient energy. The energy of the light is related to its wavelength.

2. **Identify the Wavelengths of the Given Lights**:
- Green light has a shorter wavelength than yellow light.
- Yellow light has a longer wavelength than green light.
- Blue light has an even shorter wavelength than green light.
- Red light and infrared light have longer wavelengths than yellow light.

3. **Determine the Threshold Frequency**: Since the metal surface ejects electrons when hit by green light but not by yellow light, we can conclude that green light has enough energy (or frequency) to overcome the work function of the metal, while yellow light does not.

4. **Evaluate the Options**:
- **Option A (Blue light)**: Blue light has a shorter wavelength than yellow light and therefore has higher energy. It should be able to eject electrons.
- **Option B (Heat rays)**: Heat rays (infrared) have longer wavelengths than yellow light and thus lower energy. They will not eject electrons.
- **Option C (Infrared light)**: Similar to heat rays, infrared light has a longer wavelength than yellow light and will not eject electrons.
- **Option D (Red light)**: Red light also has a longer wavelength than yellow light and will not eject electrons.

5. **Conclusion**: The only option that has a shorter wavelength than yellow light and thus higher energy is blue light. Therefore, the electrons will be ejected when the surface is hit by blue light.

### Final Answer:
The electrons will be ejected when the surface is hit by **blue light** (Option A).

---