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When ultraviolet radiation is incident o...

When ultraviolet radiation is incident on a surface , no photoelectrons are emitted If a second beam causes photoelectrons to be ejected, it may consist of

A

Infrared waves

B

X - rays

C

Visible light rays

D

Radio waves

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To solve the problem, we need to understand the concept of the photoelectric effect and the relationship between the energy of incident radiation and the emission of photoelectrons. ### Step-by-Step Solution: 1. **Understanding the Photoelectric Effect**: - The photoelectric effect occurs when light (or electromagnetic radiation) hits a material and causes the emission of electrons. - For electrons to be emitted, the energy of the incident photons must be greater than or equal to the work function (Φ) of the material. 2. **Energy of Photons**: - The energy (E) of a photon is given by the equation: \[ E = h \cdot f \] where \( h \) is Planck's constant and \( f \) is the frequency of the radiation. - The work function (Φ) is the minimum energy required to eject an electron from the surface of the material. 3. **Threshold Frequency**: - The threshold frequency (\( f_0 \)) is defined as the minimum frequency required to emit photoelectrons: \[ E = h \cdot f_0 = \Phi \] - If the frequency of the incident radiation is less than \( f_0 \), no photoelectrons will be emitted. 4. **Analyzing the Given Information**: - The problem states that ultraviolet (UV) radiation does not emit photoelectrons when incident on the surface. This implies that the energy of UV radiation is less than the work function of the material. - Therefore, the energy of the UV radiation is not sufficient to overcome the work function. 5. **Considering a Second Beam**: - For a second beam to cause photoelectrons to be ejected, its energy must be greater than the work function (Φ). - This means the frequency of the second beam must be greater than the threshold frequency (\( f_0 \)). 6. **Comparing Different Types of Radiation**: - The options given are: infrared, x-ray, visible light, and radio waves. - We need to determine which of these has a frequency greater than that of ultraviolet radiation. 7. **Order of Electromagnetic Spectrum**: - The order of electromagnetic radiation from low frequency to high frequency is: - Radio waves < Microwaves < Infrared < Visible light < Ultraviolet < X-rays - Since UV radiation does not cause emission, we need a radiation type that has a frequency higher than UV, which is X-rays. 8. **Conclusion**: - The only option that has a frequency higher than ultraviolet radiation and thus can cause photoelectrons to be emitted is **X-rays**. ### Final Answer: The second beam that causes photoelectrons to be ejected may consist of **X-rays**.
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