i do believe the answer is c not sure but correct me if im wrong
Answer:
(d) A strong electron-phonon interaction
Explanation:
Superconductivity -
The phenomenon of superconductivity is due to the attractive force between electrons from the exchange of the phonons that cause the bound pair of electrons known as cooper pairs .
A strong electron -phonon intercation is suitable condition for superconductivity and high resistance .
Thinking the small glass bead as a single point charge, the electric field generated by it is given by

where

is the Coulomb's constant

is the charge of the bead

is the distance at which we calculate the field.
Using these data, we find:
Answer:
λ = 623.2 nm
Explanation:
We are given;
separation distance; d = 0.195 mm = 0.195 × 10^(-3) m
interference pattern distance; D = 4.85 m
Width of two adjacent bright interference; w = 1.55 cm = 1.55 × 10^(-2) m
Formula for fringe width is given as;
w = λD/d
Where λ is wavelength
Thus;
λ = dw/D
λ = (0.195 × 10^(-3) × 1.55 × 10^(-2))/4.85
λ = 0.0000006232 m
Converting to nm gives;
λ = 623.2 nm