Q.
Light of wavelength λph falls on a cathode plate inside a vacuum tube as shown in the figure. The work function of the cathode surface is ϕ and the anode is a wire mesh of conducting material kept at a distance d from the cathode. A potential difference V is maintained between the electrodes. If the minimum de Broglie wavelength of the electrons passing through the anode is λe, Which of the following statement(s) is(are)true?
see full answer
Start JEE / NEET / Foundation preparation at rupees 99/day !!
21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!
An Intiative by Sri Chaitanya
a
λe increases at the same rate as λph for λph
b
λedecreases with increases in ϕand λph
c
λeis approximately halved, if d is doubled
d
For large potential difference (v>>ϕ/e), λe is approximately halved if V made four times
answer is D.
(Unlock A.I Detailed Solution for FREE)
Ready to Test Your Skills?
Check your Performance Today with our Free Mock Test used by Toppers!
Take Free Test
Detailed Solution
K.E of electron just after ejection =hcλph-ϕK.E of electron when it reaches anode =Kmax=hcλph-ϕ+Ve minimum de Broglie wavelength λe=h2Kmaxmλe=h2hcλph-ϕ+Vem Given that Ve >>ϕ (hcλph is also small for visible light)∴λeα1V ⇒ when V is made 4 times, λe will be halved.
Watch 3-min video & get full concept clarity
Get Expert Academic Guidance – Connect with a Counselor Today!

Not sure what to do in the future? Don’t worry! We have a FREE career guidance session just for you!