STATEMENT -1 `:` Work function of a metal depends on ionisation energy.
STATEMENT-2` :` One photon can eject one electron
STATEMENT -3 `:` K.E. of ejected depends on intensity of light

Options

A. T F F
B. T T F
C. T F T
D. T T T

Answer

To analyze the statements given in the question regarding the photoelectric effect, we will evaluate each statement step by step.

### Step 1: Evaluate Statement 1
**Statement 1:** Work function of a metal depends on ionization energy.

**Explanation:** The work function (ϕ) is defined as the minimum energy required to remove an electron from the surface of a metal. Ionization energy is the energy required to remove an electron from an atom or ion. Generally, for metals, the work function is related to the ionization energy because a higher ionization energy indicates that more energy is needed to remove an electron. Therefore, if the ionization energy is higher, the work function will also be higher.

**Conclusion:** Statement 1 is **True**.

### Step 2: Evaluate Statement 2
**Statement 2:** One photon can eject one electron.

**Explanation:** According to the photoelectric effect, when light (photons) strikes a metal surface, each photon can transfer its energy to a single electron. If the energy of the photon is greater than or equal to the work function of the metal, it can eject one electron. Thus, the statement correctly describes the process.

**Conclusion:** Statement 2 is **True**.

### Step 3: Evaluate Statement 3
**Statement 3:** K.E. of ejected electron depends on intensity of light.

**Explanation:** The kinetic energy (K.E.) of the ejected electron is given by the equation:
\[ K.E. = E_{photon} - \phi \]
where \( E_{photon} \) is the energy of the photon and \( \phi \) is the work function. The energy of a photon is determined by its frequency (E = hf, where h is Planck's constant and f is the frequency). The intensity of light relates to the number of photons hitting the surface per unit time, not the energy of individual photons. Therefore, while increasing intensity increases the number of ejected electrons (if the intensity is above the threshold), it does not increase the kinetic energy of each individual electron.

**Conclusion:** Statement 3 is **False**.

### Final Conclusion
- Statement 1: True
- Statement 2: True
- Statement 3: False

Thus, the correct option is that Statements 1 and 2 are true, while Statement 3 is false.

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