Question

(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 1

Answer:

λ = 9000 À .

Explanation:

Given :

Mass of electron = 9.1 × 10⁻²⁸ g

In term of kg :

Mass of electron = 9.1 × 10⁻³¹ kg

K.E. of electron = 3.0 × 10⁻²⁵ J

We know :

λ = h / √ ( 2 m × K.E. )

where h = 6.6 × 10⁻³⁴  J s

λ =  6.6 × 10⁻³⁴ / √ ( 2 × 9.1 × 10⁻³¹ × 3.0 × 10⁻²⁵ )  m

λ =  6.6 × 10⁻³⁴ / √ ( 54.6 × 10⁻⁵⁶ ) m

λ =  6.6 × 10⁻³⁴ /  7.39 × 10⁻²⁸ m

λ = 9 × 10⁻⁷ m

Now wave length in term of À :

λ = 9 × 10⁻⁷ × 10¹⁰ À

λ = 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.

Answer 2

PLEASE MARK AS BRAINLIEST!!