An electroscope is a simple device consisting

of a metal ball that is attached by a conductor
to two thin leaves of metal foil protected from air disturbance in a jar. When the ball is
touched by a charged body, the leaves that
normally hang straight down, spread apart.
Why?
1. The charge transfers to the leaves through
the metal ball. Since the leaves have different charges, they are pushed away from each
other.
2. The charge transfers to the two leaves
through the glass. Since the leaves have identical charges, they are pushed away from each
other.
3. The charge transfers to the leaves through
the glass. Since the leaves have different
charges, they are pushed away from each
other.
4. The charge transfers to the leaves through
the metal ball. Since the leaves have identical charges, they are pushed away from each
other.
5. None of these

Surely you have some thoughts on this.

The correct answer is:

1. The charge transfers to the leaves through the metal ball. Since the leaves have different charges, they are pushed away from each other.

To determine why the leaves of an electroscope spread apart when the ball is touched by a charged body, we need to consider the concept of charge transfer and electrostatic repulsion.

When an object with a charge comes into contact with the metal ball of the electroscope, charge is transferred from that object to the metal ball. This is known as charge induction or conduction. The metal ball, being a conductor, allows charges to move freely. As a result, the charges from the charged body distribute themselves over the surface of the metal ball and start to repel each other.

Option 1, "The charge transfers to the leaves through the metal ball. Since the leaves have different charges, they are pushed away from each other," is the correct explanation. Since the leaves are also made of a conducting material, the charges in the metal ball transfer to the leaves. As the leaves acquire the same charge, they repel each other due to electrostatic repulsion, causing them to spread apart.

Option 2, "The charge transfers to the two leaves through the glass. Since the leaves have identical charges, they are pushed away from each other," is incorrect because glass is an insulator and does not allow the transfer of charges between the metal ball and the leaves.

Option 3, "The charge transfers to the leaves through the glass. Since the leaves have different charges, they are pushed away from each other," is also incorrect for the same reason mentioned above.

Option 4, "The charge transfers to the leaves through the metal ball. Since the leaves have identical charges, they are pushed away from each other," is incorrect because when the charges transfer to the leaves, they acquire the same charge, not different charges.

Therefore, the correct answer is option 1, "The charge transfers to the leaves through the metal ball. Since the leaves have different charges, they are pushed away from each other."