The frequency of electromagnetic wave, which is best suited to observe a particle of radius 3 × 10⁻⁴ cm is of the order of
10¹⁵
10¹⁴
10¹³
10¹²
Correct answer: 10¹⁵
Solution
To observe a particle, the wavelength of the electromagnetic wave should be comparable to the particle's size. Using the relation λ = c/f, where c is the speed of light, and λ ≈ 3 × 10⁻⁶ m (particle size), we find f ≈ 10¹⁵ Hz.