Ultraviolet light with a wavelength of 280 nm is used in an experiment on the photoelectric effect with a lithium cathode (work function, W_o = 2.5…

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Ultraviolet light with a wavelength of 280 nm is used in an experiment on the photoelectric effect with a lithium cathode (work function, W_o = 2.5 eV). Find the stopping potential for the photoelectrons.

[h = 6.6 × 10⁻³⁴ Js, c = 3 × 10⁸ ms⁻¹, 1 eV = 1.6 × 10⁻¹⁹ J]

  1. 4.5 V
  2. 3.7 V
  3. 1.9 V ✓
  4. 2.8 V

Explanation

Tawhid (monotheism) is Islams central belief – Allah is one, unique, and alone deserving worship. Components: Tawhid al-Rububiyya (Allahs lordship – creator, sustainer), Tawhid al-Uluhiyya (worship Allah alone), Tawhid al-Asma wa Sifat (Allahs unique names and attributes).

Shirk (associating partners with Allah) is the opposite and greatest sin. Types: major shirk (worshiping others), minor shirk (showing off in worship), hidden shirk (relying on other than Allah).

Tawhid affects all life – politics, economics, ethics flow from recognizing Allahs authority. Shahada testifies to tawhid. Islam begins with and returns to this fundamental truth.

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