CURRENT ELECTRICITY
01 ELECTRIC CURRENT
03 FACTORS AFFECTING
DRIFT VELOCITY
05
Current I=
q
t - Dependence on shape
04 OHM'S LAW
J=
I
n
∆q V=I×R A
Average current Iav = ∆ t 1) Uniform shape
02
Voltage
dq
DRIFT VELOCITY
volts (V) Resistance
V V
Instantaneous current Iinst = Current ohms(Ω) I= =
dt eE Amperes (A) R ρl/A
vd=
m
τ
T1 > T2 Slope = tanθ = R Uniform cro
Average current Iav
Depends on
Free Electron Here E is uniform so, ρl τ
R=
A
1.Material (n & changes) E1=E2=E3
area under I-t graph vd1=vd2=vd3 E =E =E θ τ
2. Temperature (n & changes)
= E 1 3 2 3. Dimension (Length & Area) J1 = J2 = J
total time taken 2) Non Uniform shape Depends on
ρ= RA
=
m Non-Uniform
l ne2 τ 1.Material (n & τ changes)
3 2.Temperature (n & τ changes) E1>E2>E3
<KE> = kT E1> E2 > E3
concave
2 E accelerates Non-Ohmic Conductor
convex
J1 > J2 > J
1 the electrons V-I graph is not linear
2 x0y0
< mv2>≈ 10-21J Vd α E Vd1 > Vd2 > Vd3
2
x0
Concave area = 3 Slope of tangent dv = R But current is same
Avg. Speed = 105 m/s v=u+at 3) Relation B/w Current & Drift velocity dI
Resistance is not constant I1=I2=I3
I = nAVde
1 x0y0 Electrons are in vd=aτ 1)Slope=+ve
Convex area = 3 n= no. of e-s per unit volume
random motion Resistance = +ve
eE
vd=
m
τ 2) Slope=0
Avg. velocity = V ↑ then I ↑
Resistance=0
v1+v2+v3+...vn V
=0
E=
I 3)Slope= -ve
n Resistance = - ve
eV
vd= τ V ↑ thenI↓
Inet= 0 mI
07 CUTTING & STRETCHING
OF WIRE 09 GROUPING OF
RESISTANCE
11
Cutting of wire Series Combination
α l1
08
R1 TEMPERATURE
R2 αl2 DEPENDANCE OF RESISTANCE Current is constant
10
R3 αl3
voltage is divided CURRENT & VOLTAGE 1st Dig
Rs=R1+R2+R3+....Rn
Stretching of wire DIVIDER RULE 2nd Dig
l1 l2 Metals, α =+Ve `If resistors are Multipl
If T ↑ R↑ identical: Rs=nR Current Divider Rule R
A1 A2
Parallel Combination V =Constant Iα 1
Before stretching After stretching R
01 ELECTRIC CURRENT
03 FACTORS AFFECTING
DRIFT VELOCITY
05
Current I=
q
t - Dependence on shape
04 OHM'S LAW
J=
I
n
∆q V=I×R A
Average current Iav = ∆ t 1) Uniform shape
02
Voltage
dq
DRIFT VELOCITY
volts (V) Resistance
V V
Instantaneous current Iinst = Current ohms(Ω) I= =
dt eE Amperes (A) R ρl/A
vd=
m
τ
T1 > T2 Slope = tanθ = R Uniform cro
Average current Iav
Depends on
Free Electron Here E is uniform so, ρl τ
R=
A
1.Material (n & changes) E1=E2=E3
area under I-t graph vd1=vd2=vd3 E =E =E θ τ
2. Temperature (n & changes)
= E 1 3 2 3. Dimension (Length & Area) J1 = J2 = J
total time taken 2) Non Uniform shape Depends on
ρ= RA
=
m Non-Uniform
l ne2 τ 1.Material (n & τ changes)
3 2.Temperature (n & τ changes) E1>E2>E3
<KE> = kT E1> E2 > E3
concave
2 E accelerates Non-Ohmic Conductor
convex
J1 > J2 > J
1 the electrons V-I graph is not linear
2 x0y0
< mv2>≈ 10-21J Vd α E Vd1 > Vd2 > Vd3
2
x0
Concave area = 3 Slope of tangent dv = R But current is same
Avg. Speed = 105 m/s v=u+at 3) Relation B/w Current & Drift velocity dI
Resistance is not constant I1=I2=I3
I = nAVde
1 x0y0 Electrons are in vd=aτ 1)Slope=+ve
Convex area = 3 n= no. of e-s per unit volume
random motion Resistance = +ve
eE
vd=
m
τ 2) Slope=0
Avg. velocity = V ↑ then I ↑
Resistance=0
v1+v2+v3+...vn V
=0
E=
I 3)Slope= -ve
n Resistance = - ve
eV
vd= τ V ↑ thenI↓
Inet= 0 mI
07 CUTTING & STRETCHING
OF WIRE 09 GROUPING OF
RESISTANCE
11
Cutting of wire Series Combination
α l1
08
R1 TEMPERATURE
R2 αl2 DEPENDANCE OF RESISTANCE Current is constant
10
R3 αl3
voltage is divided CURRENT & VOLTAGE 1st Dig
Rs=R1+R2+R3+....Rn
Stretching of wire DIVIDER RULE 2nd Dig
l1 l2 Metals, α =+Ve `If resistors are Multipl
If T ↑ R↑ identical: Rs=nR Current Divider Rule R
A1 A2
Parallel Combination V =Constant Iα 1
Before stretching After stretching R
