A layer of insulating material with thermal conductivity K is ...

[lidoalex]

A layer of insulating material with thermal conductivity K is placed on a layer of another material of thermal conductivity 2K. The layers have equal thickness. What is the effective thermal conductivity of the composite sheet?
 
  A) 1.5K
  B) 3K
  C) K/3
  D) 2K/3
  E) K/5

Question 2

The radioactive isotope 226Ra (atomic number 88 ) decays to the isotope 222Rn (atomic number 86). What type of radioactive decay is this?
 
  A) beta decay
  B) electron ionization
  C) electron capture
  D) alpha decay

[jamesnevil303]

Answer to Question 1

D

Answer to Question 2

D