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If the de Broglie wavelength of an electron is equal to the 10 –3 times the wavelength of a photon of frequency 6 × 10 14 Hz, then the speed of electron is equal to : (Speed of light = 3 × 10 8 m/s, Planck's constant = 6.63 × 10 –34 J.s, Mass of electron = 9.1 × 10 –31 kg)

1. 1.7 × 10 6 m/s
2. 1.45 × 10 6 m/s
3. 1.1 × 10 6 m/s
4. 1.8 × 10 6 m/s

Correct answer: 1.45 × 10 6 m/s

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