19. Light of wavelength 310 nm falls on a lithium surface. The work function of lithium is 2.3 eV. The De Broglie wavelength of the fastest emitted photoelectrons roughly is(A) 310 nm(B) 23.2 nm(C) 13.5 nm(D) 4.6 nm(E) 0.96 nm

5. A parallel plate capacitor, with air dielectric, is charged by a battery after which the battery is disconnected. A slab of glass dielectric is then slowly inserted between the plates. As it is being inserted,(A) a force repels the glass out of the capacitor.(B) the glass makes the plates repel each other.(C) no force acts on the glass.(D) a net charge appears on the glass.(E) a force attracts the glass into the capacitor.

19. Light of wavelength 310 nm falls on a lithium surface. The work function of lithium is 2.3 eV. The De Broglie wavelength of the fastest emitted photoelectrons roughly is
(A) 310 nm
(B) 23.2 nm
(C) 13.5 nm
(D) 4.6 nm

(E) 0.96 nm

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