Idea behind a PPC

Q.

A dipole is said to be in stable equilibrium when the angle between the electric field and dipole moment is

1. zero

2. ${180}^o$

3. ${45}^o$

4. ${90}^o$

Q.

How long will a capacitor take to discharge?

Q.

The capacity of parallel plate capacitor depends on

Q. Four charges are placed on the vertices of a square as shown in figure. The net electric potential at centre of the square is

1. $\text{Zero}$
2. $10\text{V}$
3. $15\text{V}$
4. $29\text{V}$

Q. 31.The charge stored in 2uF capacitor is

Q. a 3 micro farad capacitor is charged to a potential of 100v and 2 micro farad is charged to 100v. the capacitors are then connected in parallel with opposite polarities joined together .the amount of charge flown is

Q.

A parallel plate capacitor has rectangular plates of 400 cm^2 area and are separated by a distance of 2 mm with air as the medium. What charge will appear on the plates if a 200-volt potential difference is applied across the capacitor?

Q.

The relation between $E$ and $B$ is

1. $\begin{array}{l}\left[E\right]=\left[B\right]\left[L\right]\left[T\right]\end{array}$

2. $\begin{array}{l}\left[E\right]=\left[B\right]{\left[L\right]}^{-1}\left[T\right]\end{array}$

3. $\begin{array}{l}\left[E\right]=\left[B\right]\left[L\right]{\left[T\right]}^{-1}\end{array}$

4. $\begin{array}{l}\left[E\right]=\left[B\right]{\left[L\right]}^{-1}{\left[T\right]}^{-1}\end{array}$

Q. Capacitance C depends only on the geometrical configuration (shape, size, separation) of the system of two conductors and on the nature of the dielectric separating the two conductors.

1. False
2. True

Q. A capacitor has some dielectric between its plates, and the capacitor is connected to a $DC$ source. The battery is now disconnected and then the dielectric is removed. State whether the capacitance, the energy stored in it, electric field, charge stored, and the voltage will increase, decrease, or remain constant.

Q. A capacitor of capacity C is charged to potential difference \:and another capacitor of capacity 2C is charged to potential difference 2V. The charging battries are disconected and the two capacitors are connected to each other in parallel with reverse polarity . the energy lost in this process will be.

Q. Four charges $+q,+q,-q\text{and}-q$ are placed respectively at the corners $A,B,C\text{and}D$ of a square of side $a$ arranged in the given order. $E\text{and}F$ are midpoints of side $BC$ and $CD$ respectively. $O$ is the center of the square.
$\left(ii\right)$ The electric potential at $O$ is.

​​​​​​​$[$1 Mark$]$

1. $\frac{\sqrt{2}q}{\pi {\epsilon }_{0}a}$
2. $\frac{\sqrt{3}q}{\pi {\epsilon }_{0}a}$
3. $\frac{q}{\pi {\epsilon }_{0}a}$
4. zero

Q.

The plates of a capacitor are separated by 5 mm and they are connected to a battery of 100 volt what will be the force on an electron located between the plates?

Q. A cube of side $b$ has a charge $q$ at each of its vertices. What is the electric potential at the centre of the cube?

1. $\frac{4q}{\sqrt{3}\pi {\in }_{0}b}$
2. $\frac{\sqrt{3}q}{\pi {\in }_{0}b}$
3. $\frac{2q}{\pi {\in }_{0}b}$
4. Zero

Q. Charge of 2Q and -Q are placed on two plates of a parallel plate capacitor if capaci†an ce of capacitor is C find potential difference between the plates.

Q. Current flows due north in a horizontal transmission line as shown in the figure. Magnetic field at a point $\text{P}$ vertically above it is directed

1. northwards
2. southwards
3. towards east
4. towards west

Q. When a slab of dielectric medium is placed between the plates of a parallel plate capacitor which is connected with a battery, then the charge on plates in comparision with earlier charge:

1. is less
2. is same
3. is more
4. depends on the dielectric constant

Q. the charging current for capacitor is 0.5 A .the value of displacement current is

Q.

Two capacitors of capacitance 1.0 micro farad and 2.0 micro farads are each charged by being connected across a 5.0-volt battery. they are disconnected from the battery and then connected to each other with resistivity wires so that plates of opposite charges are connected together. What will be the magnitude of the final voltage across the 2.0-micro farad capacitor?

Q. What happens In a capacitor , if the entire space is filled with a conductor instead of a dielectric, does the capacitance become infinity?

Q. A parallel plate capacitor of capacity C^° is charged to a potential V^° (I) .The energy stored in the capacitor when the battery is disconnected and the plate separation is doubled is E1(ii) the energy stored in the capacitor when the charging battery is kept connected and the separation between the capacitor plates is doubled is E2. then E1/E2 value is

Q. A conductor $\text{PQ}$ of length $b$ carries a current $i_2$ is placed perpendicular to a long conductor $\text{XY}$ carrying a current $i_1$ as shown in figure. The magnitude and direction of the magnetic force acting on $\text{PQ}$ is

Both the conductors are in $xy-$plane.

1. $\frac{{\mu }_0{i}_1{i}_2}{4\pi }\ln \left(\frac{a+b}{a}\right)\hat{j}$
   
2. $-\frac{{\mu }_0{i}_1{i}_2}{2\pi }\ln \left(\frac{a+b}{a}\right)\hat{j}$
   
3. $-\frac{{\mu }_0{i}_1{i}_2}{4\pi }\ln \left(\frac{a+b}{a}\right)\hat{j}$
   
4. $\frac{{\mu }_0{i}_1{i}_2}{2\pi }\ln \left(\frac{a+b}{a}\right)\hat{j}$
   

Q. There are $n$ identical capacitors which are connected in parallel to a potential difference $V.$ These capacitors are then reconnected in series. The potential difference between the extreme ends is

1. $nV$
2. $0$
3. $(n-1)V$
4. $(n-2)V$

Q. In Fig. the battery has a potential difference of V 10.0 V and the five capacitors each have a capacitance of 10.0 mF. What is the charge on (a) capacitor 1 and

Q. 19.An isolated parallel plate capacitor has electric energy E stored in it. If separation between the plates is decreased by 2% then energy stored in the capacitor is ?

Q. A parallel plate capacitor C has charge q and potential V b/w the plates. Work required to double the dis†an ce b/w the plates is

Q. Four electric charges $+q,+q,-q$ and $-q$ are placed at the corners of a square of side $2\text{L}$. The electric potential at point $\text{A}$, midway between the two charges $+q$ and $+q$, is:-

1. $\frac{1}{4\pi {ϵ}_0}\frac{2q}{L}(1+\sqrt{5})$
2. $\frac{1}{4\pi {ϵ}_0}\frac{2q}{L}(1+\frac{1}{\sqrt{5}})$
3. $\frac{1}{4\pi {ϵ}_0}\frac{2q}{L}(1-\frac{1}{\sqrt{5}})$
4. Zero

Q. Four point charges $-Q,-q,2q$ and $2Q$ are placed, at different corners of a square. The relation between $-Q$ and $q$ for which the potential at the center of the square is zero is:-

1. $Q=q$
2. $Q=1/q$
3. $Q=-q$
4. $Q=-1/q$

Q. The separation between plates of charged parallel plate capacitor is increased (battery was removed after charging), then

1. Field between plates decreases.
2. Energy density between plates increases.
3. Force between plates remains same.
4. Potential difference between plates remains same.

Q. An electron with kinetic energy $K_1$ enters between parallel plates of a capacitor at an angle ${}^{\prime }{\alpha }^{\prime }$ with the plates . It leaves the plates at an angle ${}^{\prime }{\beta }^{\prime }$ with kinetic energy $K_2$ . Then the ratio of kinetic energies $K_1$ : $K_2$ will be :

1. $\frac{{\sin }^2\beta }{{\cos }^2\alpha }$
2. $\frac{{\cos }^2\beta }{{\cos }^2\alpha }$
3. $\frac{\cos \beta }{\sin \alpha }$
4. $\frac{\cos \beta }{\cos \alpha }$