89 - Electricity Questions Answers
A Volt-meter of 20000 Ohm resistance is connected with R ohm resistance in series. if we apply 110 V of pd to the mechanism, the Volt meter shows 5 V reading.. so find the R...
current on both the resistances will be same
so V1/R1 = V2/R2
5/20000 = 105/R
solve
Two voltameters one of copper and another of silver, are joined in parallel. When a
total charge q flows through the voltameters, equal amount of metals are deposited.
If the electrochemical equivalents of copper and silver are z1 and z2 respectively the
charge which flows through the silver voltameter is
m = z1q1 = z2q2 (1)
and q = q1 + q2
now solve
Sir/Madam,
Can you please explain me to find potential difference between two plates of capacitor like this shown in figure. Can you Give anymore examples if possible? Thank You! (Please omit time)
after time t charge on plates of capacitor q = CE(1-e-t/RC)
then potential difference between the plates of capacitor = q/C
after a long time this potential difference = E [this can be obtained by putting t = ∞]
Mam/Sir, Please Help Me to Understand The Symmetry method And Star-Delta Method To find Eqivalent Resistance?
fig 1 and fig 2 are explaining symmetry method.
divide the circuit in two parts by a line symmetry, then calculate eq. resistance between A and O by series parellel rules then for getting eq. resisitance between A and B double the answer between A and O
Delta star is the method to convert the circuit into an equivalent circuit in which series parallel rules can be applied
By this method a set of three resistances R1, R2 and R3 can be converted to 3 new resistances 1, 2 and 3
where 1 = R1R2/(R1+R2+R3), 2 = R1R3/(R1+R2+R3) and 3 = R2R3/(R1+R2+R3)
In an electrical circuit...
H = W = i2Rt [ H directly proportional to R ]
But i2Rt can also be written as (V/R) x (V/R) x R x t = V2t/R...
H = W = V2t/R . [ H inversely proportional to R ]
therefore my question is how can heat be both directly and inversely proportional to the resistance in the circuit??
you should take the formula in which one variable is constant and for a circuit current will be constant
In an electrical circuit...
H = W = (i x i) x R x t [ H directly proportional to R ]
H = W = (V x V) x t /R . [ H inversely proportional to R ]
So is Heat Generated directly proportional or inversely proportional to the resistance in the circuit ??
H = W = (i x i) x R x t [ H directly proportional to R ]
this one is correct for the heat generated
distance b/w plate of capacitor C &q charge is increased to double . work done=??
as distance d is double thus C= Ae/2d thus capacitance will be halved so wd shld be (1/2 )q2/(C/2) ie 1/4 q2/C
BUT Sir the ans given is=( 1/2)q2/C Plzz do me a little favour by solving this query
(1/2 )q2/(C/2) = q2/C not 1/4 q2/C
so work done = new energy - previous energy
An isolated conducting sphere of radius r has given charge q then PE??
ans is q2/8πe0r
But Sir ,why the ans q2/2πe0r is incorrect??
let we have given x charge and want to give dx also to the sphere
so dE = [1/4πε0]xdx/r
now integrate and take limits of x as 0 to q
2 Equal -ve charges -q r placed at pt(0,a) and (o,-a) on y axis , one +ve charge +q at rest is left from pt(2a,0). this charge will not execute SHM . WHY?? even when F α -x condition is satisfying as force is due to both charges is acting & motion is also opposing during oscillating
Solve the question for force, you will get a condition according to which yours statement "even when F α -x condition is satisfying"
is incorrect
Two identical particles each of mass M & charge Q are placed some distance apart . If they are in equilm under mutual gravitational & electric force then calculate the order of signature of charge Q/M in SI system.
ANS = 10-10 C/kg
on comparing gravitational force and electrical force,
we get 9*109 * q2/r2 = 6.67*10-11* m2/r2
so q/m = 10-10 approx