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CURRENT ELECTRICITY ONE SHOT Electricity: (vied = How A type of energy due to the flow of charges is called electricity. (Electric current: i he flow of charge through a conductor is called electric current. Or Amount of charge flowing through a given area perpendicularly per unit time is called electric current. If 4q is the charge passing in time At then “L Electtc (oxvats| 1 = a _ da ‘ we gf Electromotive force (EMF): €wnf is may” FD of a Grivit. The electromotive force of a source can be defined as the work done by the source in taking a unit positive charge from lower potential to the higher potential . Em -|€, = W SI unit of EMF: Q hs E=W Q L SI guid ~ ac” os Wht (NI) Ohm’s law: The current flowing through a conductor is directly proportional to the potential difference applied across its ends, provided the temperature and other physical conditions like length, area etc. constant. Voc T | VOD) Getarlers J 9 Tee [at ‘. no N=RT | ad N-RT | The proportionality constant R is called resistance and it is purely independent to the value of V and I. Factors effecting resistance: Comb (i) 4?) Tenge 3 Kesistonce 0 log ta lordnchx ! {R KF 7 A RALTO ig 4 = AX 2. fre f cow sechn — g 7 A Resiche % _ | RL : = Brea fh cxoy-Sechuw : Sees MoS L Fafinhn 02h RG = RA Q l 6-T yt = Olin es “QL Current density:|The current density at any point inside a conductor is defined as the amount of charge flowing per second through a unit area held normal to the direction of the flow of charge at that point. A Cvved deasiy = Crveud “ Re eo _—— Current density for the case of current passing at certain angle: ASD —s = (NC , ) Ald x T= \AG@s0 Ss l=): jc Temperature dependence of resistivity: ((advct% ) ns, ARoc AT -O ike RU tT) ) AROK, @ Ka GA (+a 1) } So, ARK ATR OR AR = OC ATR, | 12%, Cita (1.0) ) Ko 8 = XK CU TOR, RR, = RK KCL) ReRFRATA) | Mechanism of current flow in a conductor: Drift velocity and relaxation time: | yas A 4): Drift wocity (Va): : a Vetealy by wee charge WZ EUS J J . ent R oi a O dv fe foward op besike | = teywaivss). 3 b) “Paegeuse RD: ‘ Relaxadton, the CD). 3 er ag Leet blu twa Sb Clagive : oe — WxO (al\isivg ft ony fevhde. : 4 i Relation between drift velocity and current: IT ot Ns | | ! T= (net) Ce) | € I uh 4 | = es Lek, h= ha- iis © z slechin ny : 7 | L=-en SX adel =—_ 2 } T =-eny,\ oC &Ng {Teeny EN) _ of Ohm's Law: a SS So, VERT T --enAia T= tna LU VE As, 4 = © (% Nat | ee Ms. Na=-e€ C ™ Nef \ T | eee: aay AT ) a reat Se \ =-ewh — wr] Ak Gnsladd temp ond Aimee. ars T = 2 Yee ak c Sey oN Mobility of charge carriers: (A ) Deft vlocity charge pry wut | ST wets MS [Cage ! dechne fala ppledd No : Mmabilihy = Ve fe vuboxity Elect & feld Ak: Ny € Relation between electric current and mobility fora conductor: he, T = -ev ANG ©) T =-enAAL€ Ase N = Na ce a e T “Cen ) AL. Wa WE . 2 Ch, pry ® © 
