Download Current electricity

IMPORTANT KEY POINTS OF MCAT PHYSICS
UNIIT:-CURRENT ELECTRICITY & ELECTRO -MAGNETISM
𝟏
1:-Energy stored in R-C circuit is given by, E = I2R 2C
18:-The radius of circular path or orbit of electron is given by , r =
𝟐
2:-Energy stored in capacitor in term of power is given by, E =
𝟏
𝟐
4:- Decrease in voltage due to dielectric medium of dielectric constant (k )or r is given
or
V = Vorginal / k
or C =
k × Coriginal
20:- Ratio of speed of proton to alpha particle is 2.
21:- Oersted is best known for observing that a compass needle deflects when placed near
b/w electric & magnetic phenomenon.
22:-Earth geographic north pole is magnetically a south pole & earth geographic south pole is
6:- Resistance across two terminals of n-sided polygone is given by,
𝑹(𝒏−𝟏)
Req =
𝒏
magnetically a north pole. Because opposite magnetic poles attract each others, so
7:- Capacitance of cylindrical capacitor increased by increasing both radius & length.
𝒌−𝟏
8:-Induced charge density (ind )on dielectric medium is given by, => ind = (
)
𝒌
where  = charge density on plates, k = dielectric constant.
9:- Drift speed of charged particles is given by, Vdrift =
= 𝒎𝑬/𝒆𝑩 2
a wire carrying a current. This important discovery was the first evidence of the connection
5:- Increase in capacitance due to dielectric medium of dielectric constant (k) or r is given
by, => C = r × Coriginal
𝒆𝑩
19:- Magnetic force can change the momentum of charged particle.
Pt
3:-Capacitance of isolated spherical capacitor is given by, C = 4o r
by, => V = Vorginal /r
𝒎𝑽
𝑰
similarly the pole attracted to earth geographic south pole is magnet’s south pole.
23:- A cyclotron is a device that can accelerate the charged particles to very high speed.
24:-The kinetic energy of a charged particle in magnetic field is given as => K.E = q2B2R2/ 2m
𝒏𝒒𝑨
10:- Average current in the conductor is given by, Iaverage = nqA Vdrift
11:- Current density(J)is defined as current per unit area. => J =
The pole on magnet that is attracted to earth geographic north pole is magnet’s north pole
𝑰
𝑨
25:- In CRO the fluorescent screen used is of phosphorus-31 isotope.
26:- Input Impedence of CRO is 1M .
= nqVdrift
12:- According to ohm’s law the ratio of current density & electric field is a constant 
& this constant is independent of electric field producing the current. =>  =
𝑱
𝑬
=
𝑰
𝑨𝑬
27:-Deflection sensitivity depends upon deflection voltage, separation b/w plates & plate length.
28:- Hall effect:- when a current carrying conductor is placed in a magnetic field, then a potential
where  is conductivity not surface charge density.
Difference is generated in a direction perpendicular to both current & magnetic field .This
13:- Capacitance does not increases or decreases by increasing or decreasing the charge
effect was first observed by EDWIN HALL. So it is called Hall effect.
on the plates because with increase or decrease in charge voltage also increase or decrease. 29:- When current is in x- direction & Magnetic field is in y-direction then both positive & negative
14:- Magnetic force is only a deflecting force & it does no work.
Charge carriers are deflected upward in magnetic field.
15:- Ampere law is applicable for closed path where magnetic flux remain constant.
30:- Hall voltage is given by, VH =
𝑰𝑩
𝒏𝒒𝒕
= RHIB/t
Where, RH =Hall coefficient = 1/nq
16:- Magnetic field at any point due to a current carrying straight conductor is given by,
31:-Magnetic field inside a toroid at any point is given by, B = Nµ0I / 2 r
=> B = µo I/2 r Where, r is distance of charge from current carrying conductor.
32:- The magnetic force b/w two parallel conductors is given by, F = µo l I1I2/2 r
17:- Time required to complete one revolution inside the magnetic field by a particle is given
where, I1 & I2 are currents in two conductors & r is distance b/w them.
by , => T =
𝟐 𝒎
𝒒𝑩
33:-Ampere is credited with the discovery of electromagnetism, Which is relation b/w electric current & magnetic field.
BY:- YASIR MUKHTAR ………………………………………………...<STUDENT OF MCAT>……………………………………………………………………… Page 1