DPP – 11C23
PHOTOELECTRIC EFFECT
Q1. If Threshold frequency is 7 × 10 14 𝑠𝑒𝑐 -1. Calculate the kinetic energy if frequency of the radiation is 1 × 1015 𝑠𝑒𝑐-1 .
(Ans – 19.8 × 10−20 J )
Q2. Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of λ = 6800 Å. Calculate Threshold frequency & Threshold energy.
(Ans: ν ̥= 4.41 × 1014 𝑠𝑒𝑐-1, E ̥= 2.92 × 10−19 J )
Q3. If photon of λ = 150 pm strikes on an atom & one of its inner bound electron is ejected out with a velocity of 1.5 ×1015 m/s. Calculate the energy which it is bound to the nucleus. (Ans: E ̥= 12.226 × 10−16 J, KE = 1.024 × 10−16 J )
Q4. If stopping potential of ejected electron is 0.35 V & the radiation is 256.7 nm. Calculate the threshold energy.
(Ans : E ̥= 7.18 × 10−19 J )
Q5. An electron with work function 1.9 eV ( 1 eV = 1.602 × 10−19 J ) is exposed to a radiation of wavelength 500 nm. Find the frequency ̥, wavelength ̥, Kinetic energy & Velocity of ejected electron.
(Ans : ν ̥= 4.59 × 10−19 𝑠𝑒𝑐-1 , λ ̥= 654 × 10−19 m, KE= 9.36 × 10−20 J, velocity = 4.5 × 105 m/s)