Slide 1

Slide 2 P.1 Slide 3 Rubbing Electric charges P.1 Slide 4 Matter Atom Proton + + Neutron Electron - - P.1 Slide 5 Hydrogen Electrically neutral + - - P.1 Slide 6 + + + + + + + + - - - - - - - - - - - - - - - - Slide 7 Only electron can be added or removed No. of electrons = no. of protons Electrically neutral P.1 Slide 8 + + + + + + + + - - - - - - - - - - - - - - Positive charge - - P.1 Slide 9 + + + + + + + + - - - - - - - - - - - - - - - - - - Negative charge P.1 Slide 10 Slide 11 Slide 12 Like charges repel + + + + - - - - P.1 Slide 13 Unlike charges attract + + - - P.1 Slide 14 + + - - Charged object attracts uncharged object P.1 Slide 15 Test + + ++++ ++++ ---- ---- - - P.1 Slide 16 Kinetic energy of electrons Rubbing P.2 Slide 17 Positive charges are formed because of loss of electron Negative charges are formed because of gain of electron Principle of conservation of charge - - P.2 Slide 18 Unit of charge Charge of an electron = - 1.6x10 -19 C No. of electrons in 1 C = 6.25 x 10 18 Coulomb (C) P.2 Smallest charge = - 1.6x10 -19 C Slide 19 Conductor Insulator Conduct electricity & heat energy Free electrons P.2 Slide 20 Charges repel each other Resultant force = 0 Charges are rest on the surface P.3 Charge distribution Slide 21 Higher charges density at sharp edge P.3 Charge distribution Slide 22 Positive charges are formed because of loss of electron Negative charges are formed because of gain of electron Kinetic energy of electrons Rubbing - - P.3 Slide 23 Resistor - - P.3 Slide 24 5 kV Slide 25 EHT e-e- P.3 Slide 26 EHT e-e- P.3 Slide 27 Electrons are repelled Sphere is neutral Positive & negative charges are formed Charge sharing -------- P.5 Slide 28 Electrons are repelled & flow to the sphere e-e- -------- P.5 Slide 29 Negative charges are shared between the rod & the sphere ---- P.5 Slide 30 ---- Charge sharing produces same kind of charge Amount of charge decreases after sharing P.5 Slide 31 ++++++++ Electrons are attracted Sphere is neutral Positive & negative charges are formed P.5 Slide 32 Electrons are attracted & flow to the rod ++++++++ e-e- P.5 Slide 33 Positive charges are shared between the rod & the sphere ++++ P.5 Slide 34 ++++ Charge sharing produces same kind of charge Amount of charge decreases after sharing P.5 Slide 35 Charges are attracted each other P.5 (e.g.) -4 x 10 -10 C +9 x 10 -10 C Slide 36 Positive Charges are repelled P.5 (e.g.) Total charges = +5x10 -10 C Slide 37 P.5 (e.g.) Charges in each ball = +2.5x10 -10 C Slide 38 -------- Electrons are repelled Sphere is neutral Positive & negative charges are formed Charge induction P.4 Slide 39 -------- e-e- e-e- Positive charges are attracted by the negative charges of the rod Negative charges are shared between the sphere & the earth Earthing P.4 Slide 40 Charges are shared by the ball & the Earth P.4 Bigger in size will have more charges Nearly all charges in ball will be gone Earthing Slide 41 -------- The surface area of the earth is much larger Nearly all the negative charges are lost P.4 Slide 42 Charge induction produces opposite sign of charge Amount of charge remains the same P.4 Slide 43 Electrons are attracted Positive & negative charges are formed ++++++++ Sphere is neutral P.4 Slide 44 e-e- e-e- ++++++++ Negative charges are attracted by the positive charges of the rod Positive charges are shared between the sphere & the earth Earthing P.4 Slide 45 ++++++++ The surface area of the earth is much larger Nearly all the positive charges are lost P.4 Slide 46 Charge induction produces opposite sign of charge Amount of charge remains the same P.4 Slide 47 -------- No charge Electrons are repelled Positive & negative charges are formed P.4 Slide 48 The spheres must be separated under the presence of the charged rod -------- P.4 Slide 49 Both kinds of charges are produced P.4 Slide 50 Slide 51 Slide 52 Charged sphere attracts neutral ball P.4 Slide 53 Slide 54 Slide 55 Charge sharing & the ball is repelled Charges are neutralized & the ball becomes uncharged P.4 Slide 56 Hairs are charged by sharing Hairs repel each other since they have the same charge P.4 Slide 57 Initially, hairs are neutral P.4 Slide 58 Initially, hairs are negatively charged P.4 ------------ ------------ ------------ Slide 59 Charges repel each other P.4 ------------ ------------ ------------ Slide 60 Slide 61 Neutral smoke grains are attracted by the charged conductor P.4 Slide 62 Light bulb lights up Current flows P.4 Slide 63 Small current flows Light-beam galvanometer P.4 Slide 64 + - + - Sparks P.4 Slide 65 Light up bunsen burner P.4 Slide 66 Electric wind + - P.4 Slide 67 Slide 68 Slide 69 + Slide 70 P.6 (2002) Water is neutral. Attracted by charged ruler Action and Reaction Pair. Slide 71 P.6 (2001) Can be negative charges because LIKE charges repel X Action and Reaction Pair. X Same F, but different masses. Larger Mass, less displacement Slide 72 P.7 (0427) 3 +ve charges. Repel each other 3 -ve charges. Repel each other 2 +ve charges and 1 ve charge. Not for any 2 of them X Slide 73 P.7 (0427) A (+ve) attracts B (neutral) A (+ve) attracts C (neutral) B (neutral) CANNOT attract C (neutral) X X Slide 74 P.7 (0427) A (+ve) repels B (+ve charge) A (+ve) attracts C (neutral) B (+ve charge) attracts C (neutral) X X X Slide 75 P.7 (0427) A (+ve) attracts B (-ve charge) A (+ve) attracts C (neutral) B (-ve charge) attracts C (neutral) X X X Slide 76 P.7 (0029) -+-+-+-+ - Slide 77 P.7 (9829) + - Slide 78 P.7 (9727) Slide 79 P.7 Slide 80 Electric force P. Slide 81 Attractive electric force P. Slide 82 P.7 Slide 83 Conductor Attractive force Equal amount of positive & negative charges are induced Attractive force is greater than the repulsive force because of shorter distance Repulsive force Repulsive force ++++++++ P.7 Slide 84 Insulator Equal amount of positive & negative charges are induced in each molecule Attractive force is greater than the repulsive force because of shorter distance Attractive force Repulsive force ++++++++ P.7 Slide 85 Electroscope Test of charges P.7 Slide 86 Opposite signs of charges are induced Gold leaf diverges because of repulsive force ++++++++ P.7 Slide 87 P.8 (9629) Repel each other X Attract each other Can attract neutral object Slide 88 P.8 (0344) Can attract neutral object True Net negative charge =0 False Slide 89 Discharge through air + - P.8 + - + - Slide 90 Discharge through air + - P.8 + - + - The charged rod will be less negative. Slide 91 Field Gravitational field m Weight mg Electric field Force acts on an object with some special property +- P.8 Slide 92 Shark detects other fish by the change of electric field in their bodies P.8 Slide 93 Direction of electric field lines Direction of electric force acting on a negative charge is in opposite direction Direction of electric force acting on a positive charge + - + P.9 Slide 94 + - - Slide 95 F=0 Neutral point Direction of resultant force Direction of electric field line + + + + P.9 Slide 96 +- Slide 97 The electric field line must be perpendicular to the metal plate otherwise the charge will move + -------------- P.9 Slide 98 The electric field is uniform between 2 parallel metal surface The charges appear on the inner surface + -------------- ++++++++++++++ P.9 Slide 99 Field line starts from positive charge Field line end at negative charge + - P.9 Slide 100 Field lines have NO branches or cross each other Resultant force point in one direction only P.9 Slide 101 NO field line exist inside metal + + + + + + + + +++ P.9 Slide 102 Slide 103 Slide 104 E Slide 105 Slide 106 Electric field strength Electric force acting on +1C charge + - P.9 Slide 107 P.10 e.g. W=mg = 2 x10 -15 (10) = 2 x10 -14 (N) W FeFe F e =W= 2 x10 -14 (N) + + Q=F e / E =2 x10 -14 / 1.25 x10 4 =+1.6 x 10 -18 (C) Slide 108 Draw the electric field pattern + - - P.10 + + + + + + + Slide 109 Draw the electric field pattern + - + - P.10 Slide 110 P.10 (0331) + Cancel each other Slide 111 P.10 (0331) - Cancel each other Slide 112 Applications of Electrostatics P.10 Slide 113 P.11 Slide 114 Slide 115 Slide 116 P.12 Slide 117 Positively charged drum Neutralized positive charges Carbon powder sticks on positive charges Carbon powder sticks on positively charged paper Infra-red neutralize all the charges Slide 118 EE P.12 Slide 119 I want to paint my new house !!! I want to paint my new house !!! P.12 Slide 120 Slide 121 Rub / charge the wall Electrostatic spray Electrostatic spray P.12 Less paint required Sticks strongly ++++++++++++++++++++++++++++ ---------------------- - - - Slide 122 Electrostatics Hazards P.13 Slide 123 Sparkles Slide 124 P.13 Slide 125 Dust Problem ??? P.13 Slide 126 Static charges damage microphone P.13 Slide 127 Anti-static pad P.13 Slide 128 Anti-static tyres P.13 Slide 129 Slide 130 Slide 131 Slide 132 Slide 133 to neutralize the charges in clouds to lead the charges from lightning to the ground Slide 134 P.14 True False Slide 135 P.14 Slide 136 ++++++++ Electrons are attracted Positive & negative charges are formed P.14 Slide 137 Electrons are attracted & flow to the rod ++++++++ e-e- P.14 Slide 138 ++++++++ Slide 139 Both of them are positively charged P.14 Charge sharing produces same kind of charge Slide 140 P.14 Slide 141 -------- No charge Electrons are repelled Positive & negative charges are formed P.14 Charging by Induction Slide 142 The spheres must be separated under the presence of the charged rod -------- P.14 Slide 143 Both kinds of charges are produced P.14 Slide 144 - + - + - + Slide 145 P.14 - + - + - + + - Slide 146 P.14 - + - + - Slide 147 P.15 Slide 148 The electric field is uniform between 2 parallel metal surface The charges appear on the inner surface + -------------- ++++++++++++++ P.15 Slide 149 Slide 150 -------------- ++++++++++++++ A B - Ball is negatively chargedBall is attracted to LHS Slide 151 -------------- ++++++++++++++ P.15 A B - Slide 152 -------------- ++++++++++++++ A B - Charge sharing. Ball is +ve. + Ball is attracted to RHS Slide 153 -------------- ++++++++++++++ P.15 A B + Slide 154 -------------- ++++++++++++++ A B Ball is negatively chargedBall is attracted to LHS +- Slide 155 P.15 W=mg = 9.1 x10 -31 (10) = 9.1 x10 -30 (N) W FeFe F e =eE=(1.6 x10 -19 ) (6 x10 4 ) (N) - F net =F e - W = 9.6 x10 -15 (N) If d=10 cm =0.1 m =9.6 x10 -15 (N) a=1.055 x10 16 (m/s 2 ) v 2 = 0 + 2 a d v = 45.9 x 10 6 (m/s)