Energy of a Capacitor

Q. A capacitor $4\mu F$ charged to $50\text{V}$ is connected to another capacitor of $2\mu F$ charged to $100\text{V}$ with plates of like charges connected together. The total energy before and after connection in multiples of $\left({10}^{-2}\text{J}\right)$ is

1. $1.5$ and $1.33$
2. $1.33$ and $1.5$
3. $3.0$ and $2.67$
4. $2.67$ and $3.0$

Q. In a charged capacitor, the energy resides as

1. Positive charges

2. Both the positive and negative charges

3. The field between the plates

4. Around the edge of the capacitor plates

Q.

In an electrical circuit, a battery is connected to pass $20\mathrm{C}$ of charge through it in a certain given time. The potential difference between two plates of the battery is maintained at $15\mathrm{V}.$ The work done by the battery is __________ J.

Q.

Why is Capacitor behave like a passive component of a circuit?

Q. A capacitor of capacitance $C_1=1\mu F$ charged up to a voltage $V=110V$ is connected in parallel to the terminals of a circuit consisting of two uncharged capacitors connected in series and possessing the capacitance $C_2=2\mu F$ and $C_3=3.0\mu F$. Then what is the charge flowing through the wire

1. $30\mu C$
2. $40\mu C$
3. $50\mu C$
4. $60\mu C$

Q.

Does An Inductor Have Polarity

Q. Find the total energy of the capacitors present in the circuit given below

1. $80.5\mu J$
2. $100\mu J$
3. $120.25\mu J$
4. $90.7\mu J$

Q. The energy stored by a capacitor is half of the work done by a battery to charge the capacitor.

1. False
2. True

Q.

Which oil is used In transformers ?

Q. A long wire of uniform linear charge density λ passes through a sphere of radius R as shown. Find net electric flux through the sphere.

एकसमान रेखीय आवेश घनत्व λ का एक लम्बा तार दर्शाए अनुसार R त्रिज्या के एक गोले से गुजरता है। गोले से गुजरने वाला नेट विद्युत फ्लक्स ज्ञात कीजिए।

1. $\frac{\lambda R\sqrt{3}}{2{\epsilon }_0}$
2. $\frac{\lambda R\sqrt{3}}{{\epsilon }_0}$
3. $\frac{2\lambda R}{{\epsilon }_0}$
4. $\frac{\lambda R}{{\epsilon }_0}$

Q. Energy in a capacitor is independent of the manner in which the charge configuration of the capacitor is built up.

1. False
2. True

Q.

__________ energy can be stored and easily transmitted from one place to another.

Q.

What is the function of capacitor?

Q.

What causes start capacitors to fail?

Q. Electric charges are distributed in a small volume. The flux of the electric field through a spherical surface of radius $10\text{cm}$ surrounding the total charge is $25{\text{N-m}}^2/\text{C}$. The flux over a concentric sphere of radius $20\text{cm}$ will be

1. $50{\text{N-m}}^2/\text{C}$
2. $75{\text{N-m}}^2/\text{C}$
3. $100{\text{N-m}}^2/\text{C}$
4. $25{\text{N-m}}^2/\text{C}$

Q.

What are the two types of energy meters used in our homes?

Q. If an isolated capacitor loses energy when a dielectric is introduced, where does that energy go?

1. The plates of the capacitor do work to move the dielectric between the plates.
2. The energy drains out when charges are lost from the capacitor plates.
3. The energy is taken by the current flow through the dielectric
4. Capacitor is a special case where conservation of energy does not apply.

Q. A uniformly charged conducting sphere of radius 9 m has a surface charge density of $10C/m^2$. What is the energy stored inside the sphere (i.e. from 0-R)?

1. 9MJ
2. 90MJ
3. 0J
4. 900KJ

Q. Three concentric conducting spherical shells $A,B$ and $C$ with charge $Q$ (inside $A$), $2Q$ (outer face of $B$) and $3Q$ (outer face of $C$) and radius $R,2R$ and $4R$ are placed as shown in figure. Energy stored between shell $A$ and $B$ is

1. $0$
2. $\frac{Q^2}{\pi {\epsilon }_{0}R}$
3. $\frac{Q^2}{2\pi {\epsilon }_{0}R}$
4. $\frac{Q^2}{16\pi {\epsilon }_{0}R}$

Q. Figure shows two identical parallel plate capacitors connected to a battery through a switch S. Initially, the switch is closed so that the capacitors are completely charged. The switch is now opened and the free space between the plates of the capacitors is filled with a dielectric of dielectric constant 3. Find the ratio of the initial total energy stored in the capacitors to the final total energy stored.

1. 9 : 16
2. 5 : 9
3. 2 : 3
4. 3 : 5

Q. A piece of cloud has area $25\times {10}^6{m}^2$ and electric potential of ${10}^5$ volts. If the height of cloud is 0.75 km , then energy of electric field between earth and cloud will be?

1. 250 J
2. 750 J
3. 1225 J
4. 1475 J

Q. Electric charges are distributed in a small volume. The flux of the electric field through a spherical surface of radius $10\text{cm}$ surrounding the total charge is $25{\text{N-m}}^2/\text{C}$. The flux over a concentric sphere of radius $20\text{cm}$ will be

1. $50{\text{N-m}}^2/\text{C}$
2. $25{\text{N-m}}^2/\text{C}$
3. $75{\text{N-m}}^2/\text{C}$
4. $100{\text{N-m}}^2/\text{C}$

Q. Two identical parallel plates are given charges as shown in figure. If plate area is A & plate seperation is d then heat liberated after closing switch s is.

1. $\frac{5Q^{2}d}{{\epsilon }_{0}A}$
2. $\frac{9Q^{2}d}{2{\epsilon }_{0}A}$
3. $\frac{7Q^{2}d}{3{\epsilon }_{0}A}$
4. $\frac{3Q^{2}d}{2{\epsilon }_{0}A}$

Q. Which of the following doesn't represent energy (here symbols have their usual meanings)

1. $\frac{k{q}_1{q}_2}{r}$
2. $\frac{1}{2}C{V}^2$
3. $qϵ$, where ($ϵ$ =E.M.F)
4. $\frac{1}{2}{ϵ}_0{E}^2\times Area$

Q. A capacitor of $20\mu F$ charged to $500\text{V}$, is connected in parallel to another capacitor of $10\mu F$ charged to $200\text{V}$, Find the common potential?

1. $200\text{V}$
2. $400\text{V}$
3. $600\text{V}$
4. $800\text{V}$

Q. A parallel plate capacitor with plate area A and initial separation d is connected to battery of EMF $V_0$. work done by external force to increase separation of plates from d to 2d slowly is
[Battery remains connected]

1. $\frac{{\epsilon }_{0}A{V}_0^2}{4d}$
2. $\frac{{\epsilon }_{0}A{V}_0^2}{d}$
3. $\frac{{\epsilon }_{0}A{V}_0^2}{2d}$
4. $\frac{{\epsilon }_{0}A{V}_0^2}{3d}$

Q. A capacitor of capacitance $10\mu F$ is connected to a battery providing a potential difference of 10 V across the capacitor. The energy stored inside the capacitor is?

1. $100\mu J$
2. $500\mu J$
3. $1mJ$
4. $5mJ$

Q. A capacitor of $2\mu F$ is charged as shown in the diagram. When the switch $S$ is turned to position $2$, the percentage of its stored energy dissipated is

1. $75\%$
2. $80\%$
3. $0\%$
4. $20\%$

Q. At steady state, ratio of energy stored in $C_1$ & $C_2$

1. $10:1$
2. $4:1$
3. $6:3$
4. $18:1$

Q. Three capacitors $C_1,C_2$ and $C_3$ of capacitance $4\mu \text{F}$, $3\mu \text{F}$ and $6\mu \text{F}$ are charged upto a potential difference of $5\text{V},6\text{V}$ and $4\text{V}$ respectively. If terminal $\text{a}$ is connected with $\text{f}$, terminal $\text{e}$ is connected with $\text{d}$ and $\text{b}$ is conncted with $\text{c}$, then find the amount of heat produced in the circuit?

1. $20\mu \text{J}$
2. $2\mu \text{J}$
3. $152\mu \text{J}$
4. $150\mu \text{J}$