Question

3 when a student moves a discharge wand toward the metal sphere of a van de graaff generator while it is operating, it mimics that same process as lightning. (a) which of the following best describes why does the spark occurs? a the wand is positive and the positive charges are attracted to the positive metal dome b the metal wand is polarized when it approached the generator eventually pulling enough on the negative electrons so that they discharge to the positive dome c because they are both metal and when you bring any two metals near each other there will be a spark d the wand is polarized causing its electrons to move away and then discharges its negative protons to the generator

Explanation:

When the wand approaches the Van de Graaff generator (which has a positive charge), the wand (a conductor) gets polarized. The positive charge of the dome attracts the negative electrons in the wand. As the wand gets closer, the electric field becomes strong enough to pull the electrons from the wand to the dome, creating a spark. This is similar to how lightning occurs (charge separation and discharge).

• Option A is wrong because like charges (positive - positive) repel, not attract.
• Option C is incorrect as just bringing two metals near each other doesn't always cause a spark. A significant charge difference and electric field are needed.
• Option D is wrong because protons are positively charged, not negative.

Answer:

B. the metal wand is polarized when it approached the generator eventually pulling enough on the negative electrons so that they discharge to the positive dome