An insulated wire of diameter 1.0 mm and negligible resistance is ...

[saliriagwu]

An insulated wire of diameter 1.0 mm and negligible resistance is wrapped tightly around a cylindrical core of radius 5.0 cm and length 30 cm to build a solenoid.
 
  What is the energy stored in this solenoid when a current I = 0.20 A flows through it? (0 = 4  10-7 T  m/A)
  A) 1.2  10-4 J
  B) 9.6  10-4 J
  C) 4.8  10-4 J
  D) 2.4  10-4 J
  E) 5.9  10-5 J

Question 2

An air-filled capacitor stores a potential energy of 6.00 mJ due to its charge. It is accidentally filled with water in such a way as not to discharge its plates.
 
  How much energy does it continue to store after it is filled? (The dielectric constant for water is 78 and for air it is 1.0006.)
  A) 0.077 mJ
  B) 468 mJ
  C) 0.040 mJ
  D) 6.00 mJ

[jordangronback]

Answer to Question 1

E

Answer to Question 2

A

[saliriagwu]

Excellent

[fatboyy09]

Gracias!