(a) The mass of an electron is 9.1 x 10-28 g. If its K.E.is 3.0 * 10-25 J, calculate its wavelength in Angstrom. (b) What is photoelectric effect?

(a) The mass of an electron is 9.1 x 10-28 g. If its K.E.is 3.0 * 10-2

1.	(a) The mass of an electron is 9.1 x 10-28 g. If its K.E.is 3.0 * 10-25 J, calculate its wavelength in Angstrom. (b) What is photoelectric effect?
Answer» λ = 9000 À .Explanation:Given : Mass of electron = 9.1 × 10⁻²⁸ gIn TERM of kg : Mass of electron = 9.1 × 10⁻³¹ kgK.E. of electron = 3.0 × 10⁻²⁵ JWe know : λ = h / √ ( 2 m × K.E. ) where h = 6.6 × 10⁻³⁴ J sλ = 6.6 × 10⁻³⁴ / √ ( 2 × 9.1 × 10⁻³¹ × 3.0 × 10⁻²⁵ ) mλ = 6.6 × 10⁻³⁴ / √ ( 54.6 × 10⁻⁵⁶ ) mλ = 6.6 × 10⁻³⁴ / 7.39 × 10⁻²⁸ mλ = 9 × 10⁻⁷ mNow WAVE length in term of À : λ = 9 × 10⁻⁷ × 10¹⁰ Àλ = 9000 À .Therefore wavelength is 9000 À .Photoelectric effect : When a beam of LIGHT having frequency more than threshold frequency is made to fall on metal surface , electron are ejected. These electron is CALLED photo electron and this phenomenon is called photoelectric effect.