Tag: capacitors in parallel

Questions Related to capacitors in parallel

A parallel plate capacitor has two square plates with equal and opposite charges. The surface charge densities on the plate are $+\sigma$ and $-\sigma$ respectively. In the region between the plates the magnitude of electric field is:

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

  1. $\dfrac { \sigma }{ 2{ \varepsilon } _{ 0 } } $

  2. $\dfrac { \sigma }{ { \varepsilon } _{ 0 } } $

  3. 0

  4. none of these

Show answer
Correct Option: B
Explanation:

The magnitude of the electric field due to a charged plate is given as:

$\vec E=\dfrac{\sigma}{2\varepsilon _0}$

The charge density on the upper plate is positive whereas on the lower plate it is negative.

Therefore, the electric field in the region between the two plates is the difference of the two fields.
It is given as:
$E _{net}=\dfrac{\sigma}{2\varepsilon _0}-\dfrac{-\sigma}{2\varepsilon _0}$

$E _{net}=\dfrac{\sigma}{\varepsilon _0}$

If the voltage across the parallel combination in increases which capacitor will undergo breakdown first?

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

  1. $C$

  2. $2C$

  3. Both at same moment

  4. None of these

Show answer
Correct Option: C

A capacitors of $2 \mu F$ is required is an electric circuit across a potential difference of 1.0kv. A large number of $1 \mu F$ capacitors are available which can with stand a potential difference of not more than 300V The minimum number of capacitors required to achieve this is:

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

  1. 24

  2. 32

  3. 2

  4. 16

Show answer
Correct Option: B

Two capacitors were charged to potentials 80 and 30 V. Then they connected in parallel. The potential difference across both condensers is 60 V. The ratio of the capacitances of the capacitors is

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

  1. 3 : 2

  2. 1 : 3

  3. 1 : 4

  4. 2 : 3

Show answer
Correct Option: A

The plates of a parallel plate capacitor are $4$cm apart, the first plate is at $300$V and the second plate at $-100$V. The voltage at $3$cm from the second plate is?

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

  1. $200$V

  2. $400$V

  3. $250$V

  4. $500$V

Show answer
Correct Option: A

Find the total capacitance for three capacitors of $10$f,$15$f and $35$f in parallel with each other?

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

  1. $20f$

  2. $50f$

  3. $60f$

  4. $10f$

  5. $5f$

Show answer
Correct Option: C
Explanation:

Given :    $C _1 = 10$ f                  $C _2 = 15$  f                    $C _3 = 35$  f

Equivalent capacitance for parallel combination          $C _{eq} = C _1 + C _2 + C _3$
$\therefore$   $C _{eq} = 10 + 15 + 35  = 60$  $f$

Two capacitors of capacity $C _1$ and $C _2$ are connected in parallel, then the equivalent capacity is:

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

  1. $C _1+C _2$

  2. $C _1C _2/(C _1+C _2)$

  3. $C _1/C _2$

  4. $C _2/C _1$

Show answer
Correct Option: A
Explanation:

$C _1, C _2$ are connected in parallel then equivalent capacitance is calculated as
$V=V _1=V _2$.....(1)
$q=q _1+q _2$
$\therefore CV=C _1V _1+C _2V _2$
From (1) $C=C _1+C _2$

A parallel plate capacitor is connected to a battery and the distance between the plates is decreased then which quantity is same for the parallel plate capacitor

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

  1. stored energy

  2. capacitance

  3. intensity of electric field

  4. potential difference

Show answer
Correct Option: A

Capacity of a parallel plate capacitor is $2\mu F$. The two plates of the capacitor are given $400\mu C$ and $-200\mu C$charges respectively. The potential difference between the plates is 

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

  1. $100\ V$

  2. $200\ V$

  3. $300\ V$

  4. $150\ V$

Show answer
Correct Option: D

A parallel plate capacitor consist of two circular plates each of radius 2 cm, separated by a distance of 0.1 mm. If voltage across the plates is varying at the rate of $5 \times {10^{13}}V{s^{ - 1}}$ , then the value of displacement current is:

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

  1. $5.50A$ 

  2. $ 5.56 \times 10^2 A $

  3. $ 5.56 \times 10^3 A $

  4. $ 2.28 \times 10^4 A $

Show answer
Correct Option: A