KPK Board 10th Class Physics Ch 4 Electrostatics Short Questions Answers

Ans.   Object with large number of electron are electrically neutral because they have same number of positively charged protons.

Explanation:  Every object is formed from the combination of a huge number of atoms. Every atom  has positively charged nucleus and equally negatively charged electrons surrounding the nucleus. As the number of electron increases, number  of protons also increases. They balance the charge and the body as a whole become neutral.

Ans.       Shuffling feet across a carpet cause hair to stand on your body because of static electricity produced due to frictional force due to which your hair stands.

Explanation:       When one object is rubbed against another, static electricity is produced. This is because rubbing creates a negative charge that is carried by electrons. The electrons can build up to produce static electricity. When you shuffle your feet across a carpet, you are creating many surface contacts between to you, thereby building up a static charge on your skin.

Ans.       Neutral objects are always attracted by charged objects because opposite charges come towards the charged body and same charges to the other end.

Explanation:       When we bring a negatively charged bar near a neutral sphere, positive charges inside the neutral sphere came towards negatively charged rod (due to attractive force) while negative charges to the other and ( due to repulsive force) as  shown in the figure.  Because of this reason neutral objects are always attracted by charged objects.

Ans.      The paper initially attracted to the comb because the com                          cause separation of charge in the paper.   The part of the paper pieces with positive charge is attracted to the comb. When the paper touches the comb, some of the excess negative charge in the comb is transferred to the paper. Because their charge are like, paper is then repelled as shown in figure.

Ans.       No, it is not necessary for the charged body to touch the ball of an electroscope for the leaves to diverge.

Explanation:       When we bring a negative charge near the ball, some electrons in the ball are repelled and driven to the gold leaves,  leaving the ball positively charged. Similarly, when we bring positive charge near the ball,  some electron will be attracted and move up to the ball to make it negative and leaves the leaves positively charged.  This is charge separation due to an induction and it is not necessary for the charged body to physically touch the ball.

Ans.       Electrostatic painting is better then conventional spray painting because it reduce the paint usage and helps  to distribute paint particles evenly and get coverage to every point.

Explanation:       Electrostatic paint application uses positive and negative charges apply paint in order to prevent overspray and ensure an even application. Its works by creating an electrostatic field between the object and the paint. The grounded object (the object being painted) is positively charged in order to attract the negatively charged paint molecules to its surface. By creating this electrostatic field, the grounded object acts like a magnet, pulling the paint molecules to its surface, forcing even disbursement.

Ans.          The lighting rods are normally at higher elevation than the building for the reason that  the lighting (composed of huge amount of charge) first hit the  rods (which is earthed) and not the building.

Explanation: Lighting always takes the path of least resistance, and air is pretty resistant stuff. If the lighting rod is shorter the current will find another path, like the plumbing of a house or even through solid wood. This is bad.

Ans.       We will have the same capacitor with slight changes as we will need high potential battery to charge it and the dielectric material between the plates must be different from that of plates’ material.`

Explanation:       In case of insulating material plates a high potential will be needed to deposit charges on the plates. The other charge we need to do is that the dielectric material of plates. If both the materials are same then charges will also be deposited on the dielectric causing mixing of charges (will behave like a short circuit).

Ans.       The capacitor actually stores energy in electric field.

Explanation:      Capacitor stores energy in the form of an electric field between its plates. Because the

plates are equal but oppositely charged,  a potential difference exists between them.  That means there

is energy available to do work.  And since there is a potential difference,  there is an electric  field which

points from the positive plate to the negative one.

Ans.       If you wish to store a large amount of energy in a capacitor bank,   then connect all the capacitors in parallel.

Explanation:       When in parallel, capacitor values add up, and energy storage goes in proportion.  For a given fixed voltage, parallel combination is the only way.  Series connection reduces capacitor  value and hence the stored energy.