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Light of wavelength λ ph 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 λ e , which of the following statements(s) is(are) true ? V Electrons Light – +

1. λ e increases at the same rate as λ ph for λ ph < hc/ φ
2. λ e is approximately halved, if d is doubled
3. λ e decreases with increase in φ and λ ph CAREER POINT CAREER POINT , CP Tower, IPIA, Road No.1, Kota (Raj.), : 0744-6630500 | www.ecareerpoint.com Email: info@cpil.in Page # 18 Paper-2 [ CODE – 0 ]
4. For large potential difference (V >> φ /e), λ e is approximately halved if V is made four times

Correct answer: For large potential difference (V >> φ /e), λ e is approximately halved if V is made four times

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