Notes Ch # 15

Chapter # 15

ELECTROSTATICS Q#1: Choose the correct answer of the statement from the given choices I.

There are __________ types of electric charge. (a) 1 (b) 2 (c) 3 (d) 4

II.

The atom loses an electron acquires ___________ charge. (a) Positive (b) negative (c) zero (d) neutral

III.

The origin of electric charge is _________of an atom. (a) Electron (b) nucleus (c) proton (d) neutron

IV.

The process of production of electric charge on a body due to effect of another electric charge is called______(a) Induction (b) convection (c) conduction (d) current

V.

Electroscope is used to _________ electric the charge. (a) Detect (b) measure (c) differentiate (d)

VI.

If the leaves of electroscope diverge due charge of rod then external charge is ________ to the charge of electroscope. (a) Same (b) opposite (c) identical (d) none of these

VII.

______________is used to distinguish between conductor and insulator. (a) Thermometer (b) electroscope (c) ammeter (d) telescope

VIII.

The electrostatic force between opposite charges is of ____________ (a) Attraction (b) repulsion (c) collision (d) none of these

IX.

The electrostatic force between similar charges is of ____________ (a) Attraction (b) repulsion (c) collision (d) none of these

X.

The value of K= _______. (a) 9 x 10

XI.

9

(b) 9 x 106 (c) 6 x 109 (d) 6 x 106

The space, around a charge, in which another charge can feel the effect of it is called________. (a) Electric field (b) electric potential (c) electric force (d) electric work

XII.

Force per unit charge is called __________. (a) Electric field (b) electric potential (c) electric force (d) electric work

XIII.

Electric intensity is a ____________ quantity. (a) Vector (b) scalar (c) electric (d) none of these

XIV.

The positive charge move ________ the lines of force. (a) opposite to (b) along (c) perpendicular to (d) none of these

XV.

The electric lines of force emerge from ___________ charge. (a) Positive (b) negative (c) neutral (d) any

XVI.

The electric lines of force enter into the ________ charge. (a) Positive (b) negative (c) neutral (d) any

XVII.

Where electric lines of force become closer there electric field will be___________. (a) Increase (b) decrease (c) stronger (d) weaker

XVIII.

Where electric lines of force become broader there electric field will be___________. (a) Increase (b) decrease (c) stronger (d) weaker

XIX.

The work done per unit charge is called __________. (a) Electric field (b) electric potential (c) electric energy (d) electric force

XX.

The energy supplied by a unit charge as it moves from one point to the other is called ________. (a) Potential difference (b) electric potential (c) electric field (d) electric force

XXI.

If a positive charge is transferred from a point of lower potential to a point of higher potential. Energy would have to be ________ to it.

(a) Supplied (b) gained (c) delivered (d) deposited XXII.

The device which is used to store electric energy is called _________. (a) Electroscope (b) telescope (c) capacitor (d) resistor

XXIII.

The ability of a capacitor to store electric energy is called _____________. (a) Resistance (b) capacitance (c) inductance (d) none of these

XXIV.

In the series combination the capacitance of capacitors will _________. (a) Increase (b)add up (c) decrease (d) reduce

XXV.

In the parallel combination the capacitance of capacitors will _________. (a) Increase (b)add up (c) decrease (d) reduce

XXVI.

Cylindrical, parallel plate and spherical capacitors are typed of capacitors according to there___. (a) Shape (b) dielectric (c) material used (d) capacitance

XXVII.

Variable and constant capacitors are types of capacitors due to their__________. (a) Shape (b) dielectric (c) material used (d) capacitance

Q#2: Give short answer of the following questions I.

Define electric charge?

Ans: The access or deficiency of electron in atoms of any material is called charge. If a body looses electron it acquires positive charge, while a body which gains electron will become negatively charged. II.

How many types of electric charge are, define each?

Ans: There are two types of electric charge, positive and negative. As we know that the net charge of an atom is zero but it loses an electron it becomes positively charged and when it gain an electron it becomes negatively charged. III. Ans:

Which charges repel and which attract?

like charges always repel each other while unlike charges attract each other. IV.

What is the origin of electric charge?

Ans: An electric charge is induced or produced on any material when its number of electrons and that of proton becomes unbalance, which are normally equal. So we can say that the origin of electric charge is electron. Because this imbalance-meant is only possible when an atom losses or get an electron from another atom. V.

Define electric induction?

Ans: The phenomenon in which a charged body produces an opposite charge at one end and a like charge at the other end of an insulated conductor is known as electrostatic induction. VI.

Define electrostatic?

Ans: The branch of physics in which we study the effects of charge when they are at rest. VII.

What is an electroscope?

Ans: A device used for detecting and testing the nature of charge of any body is known as electroscope. VIII.

Why we use an electroscope?

Ans: An electroscope is used to detect and test the polarity of charge of any body. IX.

If the leaves of electroscope, having positive charge, diverge than what is the charge on rod?

Ans: As the leaves diverge and have positive charge so the charge on rod should be same (positive), because same charges repel each other.

X.

State coulomb’s law?

Ans: The force of attraction or repulsion between two charges is directly proportional to the product of their charges and inversely proportional to the square of distance between them. XI.

Write the expression of coulomb’s law?

Ans: The expression of coulomb’s law is defined as

F = K q1 q2 / r2 XII.

What is the expression of proportionality constant of coulomb’s law?

Ans : The expression of G is defined as K = 1 / 4 π Є0 K= 9x109 N m2 C-2

and the value of XIII.

Define electric field?

Ans: The electric field of a charge is a region of space surrounding it, in which a charge can feel its electrostatic effect in the form of force. OR The force per unit charge of an electric charge is defined as electric field. It is defined as E = K q / r2 XIV.

OR

E = F/q

Where electric field does strong and where does it weak?

Ans: The electric field is strong close to the charge and weak far away from the source charge. Or the electric field is strong where the electric lines force is closer and it is weak where electric lines of force are brooder. XV.

In which direction positive charges move under the action of electric field?

Ans: The positive charge will move along the lines of force in the same direction under the action of electric field.

XVI.

In which direction negative charges move under the action of electric field?

Ans: The negative charge will move along the lines of force in the opposite direction under the action of electric field.

XVII.

Define electric potential?

Ans: The electric potential at any point in an electric field is defined as, the potential energy of a unit positive charge placed at that point which is equal to the amount of work done in bringing it from infinity to that point. OR The electric potential is the amount of work done in bring a unit positive charge from infinity to the point into the electric field. XVIII.

Define electric potential difference?

Ans: The electrical potential difference between two points can be defined as, the energy supplied/gained by a unit charge as it moves from one point to the other in an electric field. XIX.

When energy does is supplied and when it gained from a unit positive charge during its motion in electric field?

Ans: If a positive charge is transferred from a point of lower potential to a point of higher potential, energy would have to be supplied to the other, and if a positive charge is transferred from a point of higher potential to a point of lower potential, energy would have to be gained from the other. XX.

When energy does is supplied and when it gained from a unit negative charge during its motion in electric field?

Ans: If a negative charge is transferred from a point of lower potential to a point of higher potential, energy would have to be gained from the other, and if negative charge is transferred from a point of higher potential to a point of lower potential, energy would have to be supplied to the other. XXI.

Write the use of electrostatic phenomenon in industry?

Ans: The electrostatic phenomena is used to separate particles and smoke from gases coming out the chimneys, in applying paint on the surface of different articles. XXII.

Define capacitor?

Ans: A device which is used to store electrical charge is called capacitor. XXIII.

Define capacitance of a capacitor?

Ans: The capability of a capacitor to store electric charge is known as capacitance. XXIV.

Write the expression of capacitance and voltage of capacitor?

Ans: The expression to determine the amount of charge stored on a capacitor is as

Q = CV

XXV.

Define series combination of capacitor?

Ans: A combination of capacitors in which only one way for the flow of charges is called series combination of capacitors. OR The combination of capacitors in which, capacitors are connected plate to plate is called series combination of capacitors. XXVI.

Define parallel combination of capacitors?

Ans: A combination of capacitors in which only one way for the flow of charges is called series combination of capacitors. OR The combination of capacitors in which, capacitors are connected plate to plate is called series combination of capacitors.

XXVII.

In which combination the capacitance of capacitors will increase?

Ans; In parallel combination the total capacitance of capacitors is added directly, so we can say that the capacitance of capacitors will increase in Parallel combination of capacitors. XXVIII.

In which combination the capacitance of capacitors will reduce?

Ans; In series combination the resultant capacitance of capacitors is added inversely, so we can say that the capacitance of capacitors will be less than the capacitances of each capacitor in Parallel combination of capacitors. XXIX.

In which combination voltages distribute?

Ans: In the series combination of capacitors the total applied voltage will distribute among all the capacitors of the circuit. XXX.

In which combination of voltage will remain invariant?

Ans: In the parallel combination of capacitors the total applied voltage will not distribute among all the capacitors of the circuit and remain same at each terminal. XXXI.

In which combination of capacitors charge will not distribute?

Ans: In the series combination of capacitors the total applied charge will not distribute among all the capacitors of the circuit and remain same.

XXXII.

In which combination of capacitors charge will distribute?

Ans: In the parallel combination of capacitors the total applied charge will distribute among all the capacitors of the circuit. XXXIII.

Write different types of capacitors according to material used in them?

Ans: Capacitors are classified according to the material used in them as follows (a) Mica capacitor (b) paper capacitor (c) oil capacitor (d) plastic capacitor (e) air capacitor XXXIV.

Write different types of capacitors according to the shape (geometry)?

Ans: Capacitors are classified according to their shapes (geometry) as follows (a)Parallel plate capacitor (b) cylindrical capacitor (c) Spherical capacitor XXXV.

Define variable capacitor?

Ans: A parallel plate capacitor arranged in such a way that the area of the plates facing each other can be changed then it is called a variable capacitor. OR A capacitor, the capacitance, of which could be changed according to our need is called a variable capacitor. XXXVI.

Define constant capacitor?

Ans: A capacitor, the capacitance, of which could not be changed according is called a constant capacitor XXXVII.

Explain the construction of variable capacitor?

Ans: If in a parallel plate capacitor some arrangement is made so that the area of the plates facing each other can be changed then if is called variable capacitor. It is usually a combination of many capacitors with air as dielectric. OR The variable capacitor consists of two sets of plates. One set remains static while the second one can rotate so the distance between the plates remains the same and they do not touch each other.

Long Questions Q#3: Write a note on the electroscope and its uses? Q#4: State and explain the coulomb’s law of electrostatic force between charges? Q#5: Explain the electric field and drive its equation? Q#6: Explain the formation of electric lines of force? Q#7: Explain the series combination of capacitors and drive its equation? Q#8: Explain the parallel combination of capacitors and drive its equation?? Q#9: Explain different types of capacitors?