Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice physics capacitance capacitors in parallel combination of capacitors capacitors in parallel and series

From a supply of identical capacitors rated $8\;\mu F, 250 \;V$ the minimum number of capacitors required to form a composite of $16\;\mu F, 1000 \;V$ is

  1. 2

  2. 4

  3. 16

  4. 32
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The number of capacitance to be connected in series $\displaystyle n=\frac{voltage \  rating \ required}{voltage\  rating \ of \ a \ capacitor \ given}=\frac{1000}{250}=4$
Equivalent capacitance, $\displaystyle C _{eq}=(\frac{1}{8}+\frac{1}{8}+\frac{1}{8}+\frac{1}{8})^{-1}=(\frac{4}{8})^{-1}=2$
Number of rows required $\displaystyle =\frac{capacitance \ required}{capacitance \  of \ each \  row}=\frac{16}{2}$
Thus the minimum number of capacitors to be required $=4\times 8=32$

Multiple choice physics capacitance capacitors in parallel combination of capacitors capacitors in parallel and series

In order to increase the capacity of parallel plate condenser one should introduce between the plates, a sheet of

  1. mica

  2. tin

  3. copper

  4. stainless steel
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

mica as it is having higher conductivity$.$

So$,$ increase the capacity of parallel plate condenser one should introduce between the plates$,$ a sheet of $mica.$
Hence,
option $(A)$ is correct answer.

Multiple choice physics capacitance capacitors in parallel combination of capacitors capacitors in parallel and series

A parallel plate capacitor is made by stacking $n$ equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is $C$, then the resultant capacitance is-

  1. $(n-1)C$
  2. $(n+1)C$
  3. $C$
  4. $nC$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$n$ plates connected alternately give rise to $\left(n – 1\right)$ capacitors connected in parallel $\therefore$, Resultant capacitance $=\left(n – 1\right)C$.

Multiple choice physics capacitance capacitors in parallel combination of capacitors capacitors in parallel and series

A parallel plate condenser has plates of area $200\mathrm { cm } ^ { 2 }$ and separation $0.05\mathrm { cm } .$ The space between plates have been filled with a dielectric having $\mathrm { k } = 8$ and then charged to $300$ volts. The stored energy:

  1. $121.5 \times 10 ^ { - 6 } \mathrm { J }$
  2. $28 \times 10 ^ { - 6 } \mathrm { J }$
  3. $112.4 \times 10 ^ { - 5 } \mathrm { J }$
  4. $1.6 \times 64 \times 10 ^ { - 5 } \mathrm { J }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$C = \dfrac{{KA{ \in _0}}}{d} = \dfrac{{3 \times 200 \times {{10}^{ - 4}} \times 8.85 \times {{10}^{ - 12}}}}{{5 \times {{10}^{ - 4}}}}$

$ = 27 \times {10^{ - 10}}F$
$E = \dfrac{1}{2}C{V^2} = \frac{1}{2} \times 27 \times {10^{ - 10}} \times 300$
$ = \dfrac{{243}}{2} \times {10^{ - 6}}$
$ = 121.5 \times {10^{ - 6}}J$
Hence,
option $(A)$ is correct answer.

Multiple choice physics capacitance capacitors in parallel combination of capacitors capacitors in parallel and series

A Parallel platecapacitor made of circular plates each of radius $R=6.0cm$ has a capacitance 100$\mathrm { pF }$ is connected to 230$\mathrm { V }$ of $\mathrm { AC }$ supply of 300 rad/sec.frequency. The rms value of displacement current

  1. $6.9\mu A$
  2. $2.3\mu A$
  3. $9.2\mu A$
  4. $4.6\mu A$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Given$:-$

$R=6.0cm$
$C = 100pF$
$ = 100 \times {10^{ - 12}}F$
$w = 300\,rad/s$
${I _{rms}} = 230 \times 300 \times 100 \times {10^{ - 12}}$
$ = 6.9 \times {10^{ - 9}}$
$ = 6.9\mu A$
Hence, 
option $(A)$ is correct answer.

Multiple choice physics capacitance capacitors in parallel combination of capacitors capacitors in parallel and series

Two parallel plates have equal and opposite charge. When the space between them is evacuated. the electric field between the plates $2 \times {10^5}\,V/m.$ When the space is filed with dielectric the electric field becomes ${10^5}\,V/m$ The dielectric constant of he dielectric material is 

  1. $2$
  2. $4$
  3. $5$
  4. $9$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Dielectric constant$:-$

$K = \dfrac{{{E _0}}}{E}$
$ = \dfrac{{2 \times {{10}^5}}}{{1 \times {{10}^5}}} = 2$
Hence,
option $(A)$is correct answer

Multiple choice physics capacitance capacitors in parallel combination of capacitors capacitors in parallel and series

Two capacitors of capacitance $2\, \mu F$ and $4\, \mu F$ are charge to $200\, V$ and $100\, V$ respectively. They are then connected in parallel to each other. What is the potential across each capacitor ?

  1. $116\, V$
  2. $133\, V$
  3. $148\, V$
  4. $164\, V$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Common potential V = (C1V1 + C2V2) / (C1 + C2) = (2*200 + 4*100) / (2 + 4) = (400 + 400) / 6 = 800 / 6 = 133.33 V.