chapter three induction in a straight wire

Question 1

proof on the relation on stright wire

Answer 1

consider a straight wire of length [L] is moved perpendcular through a magnetic filed to cover distance [X] on U-shaped conductor

draw in page 127

E_ind = –DØ_m \ Dt since , Ø_m = B x DA

E_ind = –B x DA \ Dt since , A = L x DX

E_ind = –BxLxDX \ Dt since , V_el = distance (DX) \ Dt

E_ind = –B x L x V_el

if the wire moves making angle [seta] with the magnetic flux lines

E_ind = –BxLxV_el SIN seta

NOTE B ⇒ extrenal

L ⇒ wire

Question 2

fleming right hand rule

uses and how to use

Answer 2

• USES ; To detrmine the direction of the induced current in a straight wire move perpendiculer to external magnetic filed
• extend the thump , forefinger and middle finger of the right hand perpendiculer to each other , if forefinger points to the direction of the filed and the thump in the direction of motion then the middle finger will point to the direction of the induced current

Question 3

when the induced E.M.F

be maximum , be zero

Answer 3

when the wire move peerpendculer to the extrnal magnetic filed seta = 90 E_ind = BLVSINseta = BLV

when the wire move parrallel to the extrnal magnetic filed

seta = 0 E_ind =BLVSINseta =0

Question 4

the wire may move perpendculer and no induced current GR

Answer 4

because the wire is not connected to closed circuit

NOTE ; there is E.M.F induced

Question 5

the wire may move between two poles of magnet and induced E.M.F is not produced

Answer 5

if the wire is moved parallel to the magnetic flux lines

seta = 0 E_ind = B L V SINseta = zero

Question 6

in straight wire the current grows quickly , and it grows slowly in a coil bwhen the electric circuit is switched on GR

Answer 6

because there is no self induction between in the straight wire but the current grows in the first turn so it acts as a shell magnet produces magnetic filled cut the other turns so opposite induced current will be generated to oppose growing the origanal current

Question 7

in straight wire the current grows quickly , and it grows slowly in a coil bwhen the electric circuit is switched of GR

Answer 7

because there is no self induction in the straight wire but the current will decay and also its magnetic filled that link the turns of the coil wiil decay so forword current will be induced to resist the decreasing of the current

Question 8

A straight wire placed normal to a magnetic filed will move when an electric current passes through it

Answer 8

• uniform magnetic filed is formed between the poles of the magnet from N to S
• magnetic filed as concentric circules will be formed due to passing of the electric current through the straight wire either clockwise or anti clock wise
• when the wire is placed normally on the magnetic filed the two magnetic fileds will be in same direction in one side so their resultant will be larger and replution takes plsace , while they will be in two opposite direction in thr other side so their resultant will be smaller and attraction takes place