Advertisements
Advertisements
प्रश्न
The work function of a metal is 2.31 eV. Photoelectric emission occurs when the light of frequency 6.4 × 1014 Hz is incident on the metal surface. Calculate
- the energy of the incident radiation,
- the maximum kinetic energy of the emitted electron and
- the stopping potential of the surface.
Advertisements
उत्तर
(i) Frequency of incident radiation = ν = 6.4 × 1014 Hz
Energy of incident radiation = E = hν = 6.6 × 10−34 × 6.4 × 1014 = 42.24 × 10−20 J
(ii) KEmax = hν − Φ0
∴ KEmax = 42.24 × 10−20 − 2.31 × 1.6 × 10−19 = 5.28 × 10−20 J
(iii) If stopping potential = VS, then
eVS = KEmax
∴ VS = `"KE"_"max"/"e"`
= `(5.28 xx 10^-20)/(1.6 xx 10^-19)`
= 3.3 × 10−1
= 0.33 V
APPEARS IN
संबंधित प्रश्न
Why should gases be insulators at ordinary pressures and start conducting at very low pressures?
The work function of the following metals is given : Na 2.75 ev, K = 2.3 eV, Mo = 4.17 eV and Ni = 5.15 eV. Which of these metals will not cause photoelectric emission for radiation of wavelength 3300 Å from a laser source placed 1 m away from these metals? What happens if the laser source is brought nearer and placed 50 cm away?
Would you prefer a material with a high melting point or a low melting point to be used as a cathode in a diode?
The cathode of a diode valve is replaced by another cathode of double the surface area. Keeping the voltage and temperature conditions the same, will the place current decrease, increase or remain the same?
Let i0 be the thermionic current from a metal surface when the absolute temperature of the surface is T0. The temperature is slowly increased and the thermionic current is measured as a function of temperature. Which of the following plots may represent the variation in (i/i0) against (T/T0)?
Answer the following question.
Define the term "Threshold frequency", in the context of photoelectric emission.
The wavelength λe of an electron and λp of a photon of same energy E are related by ______.
If a light of wavelength 330 nm is incident on a metal with work function 3.55 eV, the electrons are emitted. Then the wavelength of the wave associated with the emitted electron is (Take h = 6.6 × 10–34 Js)
Define the work function of a metal. Give its unit.
What do you mean by electron emission? Explain briefly various methods of electron emission.
