Answer:
b) R/4 (There seems to an error in mentioning the multiple choices of this question, please see below explanation of correct calculations for this question.)
Explanation:
dimension of the conductor before melting is l, r
reistivity is p
R=(p*l)/(pie*r2)
after reforming length is reduced to L=l/4
volume in both the cases will be same
i.e. pie * r^2 * l =pie * R^2 * L
r^2 * l = R^2 * (1/2)l
due to this radius will become R=sqrt(2) * r
now new reistance is given by Rx=(p * L)/(pie * R^2)
i.e. Rx=(p * l/2)/(pie * r^2 * 2)
after simplification RX=((p * l)/(pie * r^2))/4
i.e. Rx=R/4
I don't know fully, but I know S waves can't travel through liquids. Hope that helps a little!
the answer is d it reflects all the wavelengths of visible light.
