Electricity

51.	When a glass rod is rubbed with silk, the rod-
	A. Negative charge is produced on silk but not charge on the glass rod
	B. Equal but opposite charge are produced on the both
	C. Equal and similar charges are produced on the both
	D. Positive charge is produced on the glass rod but no charge on the silk Option “B” is correct. When any two bodies are rubbed together, electrons from the body in which they are loosely attracted by the nucleus are transferred to another body. Thus when the glass rod is rubbed with silk cloth electron flows from the glass rod to the silk. One body becomes positively charged and the other negatively charged. $∙$ The amount of negative charge appearing on the slik cloth depends on the number of electrons received by it. And the amount of positive charge appearing on the glass rod depends on the number of electrons lost by it. $∙$ Thus, equal but opposite charges appear on the two bodies.

52.	Where do charges reside in the case of a charged conductor?
	A. Inside the conductor
	B. On the outer surface of the conductor
	C. On the inner surface of the conductor
	D. Anywhere outside the conductor Option “B” is correct. Since the electric field is zero inside the conductor, the mutual repulsion of like charges from Coulomb’s Law demands that the charges be as far apart as possible. Hence on the surface of the conductor, the net electric charge of a conductor resides entirely on its surface.

53.	The force between two electric charges is related to__
	A. Ampere’s law
	B. Coulomb’s law
	C. Faraday’s law
	D. Rules of Om Option “B” is correct. According to Coulomb’s law, the force of attraction or repulsion between two charged bodies is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

54.	When the distance between two charged particles is halved, then the force between them becomes :
	A. Half
	B. Dual
	C. Quadruple
	D. One fourth Option”C” is correct.

55.	When two bodies have similar charges are kept close to each other, then they will:
	A. Repel each other
	B. Attract each other
	C. Neither attract nor repel
	D. Can’t say Option “A” is correct

56.	When an ebonite stick is rubbed with the skin of a cat, the ebonite stick-
	A. Positive
	B. Negative
	C. Cannot be said
	D. First negatively charged then positively charged Option “B” is correct. Whenever an ebonite rod is rubbed with cat’s fur, the rod develops negative charge. Ebonite rod is special vulcanized rubber used in many ways like electrical insulation materials, instruments, fountain pens etc. this ebonite rod has tightly bound particles which do not easily lose electrons from it. So when it is rubbed with cat’s fur, the fur easily loses electrons from it but the rod does not. So the rod gains negative charge and fur gains positive charge. The same process happens when a glass rod is rubbed with silk cloth. In both phenomena all materials gain some charge. This is due to the chemical bonding between the surfaces. They transfer their charges to get neutralized. According to the law of conservation of charges, charges can neither be created nor be destroyed, they can only be transferred from one form to another. This law is applicable in all conditions. So in these phenomena charges are not created they just get transferred from one body to another because of charge density. Therefore ebonite rod gets negative charge and fur acquires positive charge. Therefore, option (B) is the correct answer.

57.	When a charge is transferred from one object to another, Identify which of the following are actually transferred?
	A. Electrons
	B. Protons
	C. Neutrons
	D. Photons Option “A” is correct. When charge is transferred , electrons are transferred actually because electrons are mobile and lighter than protons , besides this protons are bound in nucleus , so it is easy for electrons to move compared to protons . Neutrons and photons are chargeless particle so they can’t transfer the charge .Quarks are fundamental particles of protons and neutrons so they don’t participate in charge transfer .

58.	You go in the car if lightning is going to fall from the sky, to be safe-
	A. Close the car windows
	B. Open the car windows
	C. Get out of the car and sit down
	D. Sit on top of the car Option “A” is correct. Electric field inside the conductor is always zero i.e a conductor acts as a shield for the objects placed inside it and prevents it from the effect of external electric field. That’s why it is safer to be inside the car as the metal surface of the car acts as a shield for the person and so prevents the person fron lightening.

59.	The force between two stationary charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
	A. Ohm’s law
	B. Kirchhoff’s law
	C. Coulomb’s law
	D. Faraday’s law Option “C” is correct. According to Coulomb’s law, the force of attraction or repulsion between two charged bodies is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. It acts along the line joining the two charges considered to be point charges.

60.	Work done in moving a unit positive charge from one point to other in an electric circuit is called __
	A. resistance
	B. potential difference
	C. conduction
	D. Strength of electric current Option “B” is correct. The Work done in moving a unit positive charge from one point to other in an electric circuit is called as potential difference. The potential difference is expressed in terms of volts (V). According to Ohm’s law it is mathematically expressed as $V$ = $I R$ where, I = Current R = Resistance.

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