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Photoelectric equation: kinetic energy of ejected electrons, work function or wavelength

This type of question, asked 3 times: 2021 Paper 19, 23 Jan 2026 S2, 2 Apr 2026 S2. All 3 questions below, oldest first.

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  1. Question 1

    2021 Paper 19

    54
    A metal surface is exposed to 500 nm500\text{ }nm radiation. The threshold frequency of the metal for photoelectric current is 4.3×1014 Hz4.3 \times10^{14}\text{ }Hz. The velocity of ejected electron is ____ ×105 ms−1\times10^{5}{\text{ }ms}^{- 1} (Nearest integer) [Use: h=6.63×10−34Js,me=9.0×10−31 kgh = 6.63 \times10^{- 34}Js,m_{e}= 9.0 \times10^{- 31}\text{ }kg ]

  2. Question 2

    23 Jan 2026 S2

    43
    The work functions of two metals (MAM_{A} and MBM_{B}) are in the 1:21:2 ratio. When these metals are exposed to photons of energy 6 eV , the kinetic energy of liberated electrons of MA:MBM_{A}:M_{B} is in the ratio of 2.642 : 1. The work functions (in eV ) of MAM_{A} and MBM_{B} are respectively.

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  3. Question 3

    2 Apr 2026 S2

    46
    The surface of sodium metal is irradiated with radiation of wavelength x nm . The kinetic energy of ejected electrons is 2.8×10−20 J2.8 \times 10^{- 20}\text{ }J. The work function of sodium is 2.3 eV . The value of x is ____\_\_\_\_ ×102 nm\times 10^{2}\text{ }nm. (Nearest integer) (Given : h=6.6×10−34 J s;1eV=1.60×10−19 Jh = 6.6 \times 10^{- 34}\text{ }J\text{ }s;1eV = 1.60 \times 10^{- 19}\text{ }J; c=3.0×108 ms−1c = 3.0 \times 10^{8}{\text{ }ms}^{- 1} )