A compound lens is made by joining the plane surfaces of two thin ...

[viki]

A compound lens is made by joining the plane surfaces of two thin plano-convex lenses of different glasses. The radius of curvature of each convex surface is 80 cm. The indices of refraction of the two glasses are 1.50 and 1.60.
 
  What is the focal length of the compound lens?
  A) 71 B) 75 C) 67 D) 69 E) 73

Question 2

Two charges QA = +q and QB = - 3q are located on the x-axis at x= 0 and x= d respectively. Where is the electric potential equal to zero?
 
  A)
 
  x= 3d/4
  B)
 
  x= d/3
  C)
 
  x = d/4
  D)
 
  x= 2d/3
  E)
 
  x= d/2

[katheyjon]

Answer to Question 1

E

Answer to Question 2

C

[viki]

Gracias!

[xiaomengxian]

Excellent