Capacitors

Q.

What is the working principle of a capacitor?

Q. Electric field intensity due to linear charge distribution at broad on position?

Q.

A current through a wire depends on time as $i={\alpha }_{0}t+\beta t^2$ where ${\alpha }_0=20A/s$ and $\beta =8A{s}^{-2}$. Find the charge crossed through a section of the wire in $15s$.

1. $2100C$

2. $260C$

3. $2250C$

4. $11250C$

Q. Which of the following can be classified as an input device?

1. Keyboard
2. Printer
3. Mouse
4. Monitor

Q. Why is an gold leaf electroscope provided with a metal foil which is earthed

Q.

Can I use an AC capacitor for DC?

Q.

What is the difference between electronics and electrical?

Q. Two identical parallel plate capacitors are placed in series and connected to a constant voltage source V volts.If one of the capacitors is completely immersed in a liquid with dielectric constant K the potential difference between the plates of the other capacitor will change to?

Q. How the charge is generated ?

Q.

An electric bulb connected to a $220V$ supply line draws a current of $0.05A$. Calculate the amount of coulombs per second flowing through the bulb.

Q.

In BJT, maximum current flows in which of the following?

1. in the emitter

2. in the collector

3. in the base

4. through CB junction

Q. Write the application of capacitors.

Q.

The law which governs the force between electric charges is known as?

Q.

What is Coulombs law?

Q. Why do unlike charges attract

Q. N drops of mercury of equal radii and possesing equal charges combine to form a big drop. What is the charge capacitance and potential of the drop?

Q. An ohm is defined as one volt per ampere. A farad, the unit for capacitance, is a coulomb per volt. Identify the unit of an ohm times farad.

1. Resistance
2. Voltage
3. Energy
4. Time
5. Charge

Q.

The conventional direction of flow of current is______________.

Q. In the circuit shown in figure $C=6\mu F$. The charge stored in capacitor of capacity $C$ is?

1. $Zero$
2. $90\mu C$
3. $40\mu C$
4. $60\mu C$

Q. Series equivalent of two capacitors is 3microfarad and parallel equivalent is 16microfarad. What is the value of individual capacitors?

Q. A cylindrical capacitor has two co-axial cylinders of length 20cm and radii 1.5cm and 1.6cm. The outer cylinder is earthed and inner cylinder is given a charge of 4 micro coulomb.Then what will be the capacitance of the system (neglect end effects)?

Q. n Identical cells each of emf E and internal resistance r are joined in series to form a closed circuit. One of the cell A is joined with reversed polarity . The potential differnce across A is?

Q. Two identical parallel plate capacitors are connected in series and then joined with a battery of 100 V. A sheet of dielectric constant 4.0 is inserted between the plates of second capacitor. The potential difference across the capacitor will be

Q. A circuit has a section AB shown in the figure. The emf of the source equals $\epsilon =10$V, the capacitance as of the capacitors are equal to $C_1=1.0\mu F$ and $C_2=2.0\mu F$, the potential difference ${\varphi }_A-{\varphi }_B=5.0$V. The voltage across capacitor $C_1$ & $C_2$ is respectively.

1. $10V,5V$
2. $10/3V,10/3V$
3. $0V,0V$
4. $5/3V,5/3V$

Q. A capacitor $C_1=1.0\mu F$ is charged up to a voltage $V=60V$ by connecting it to a battery $B$ through the switch (1). Now $C_1$ is disconnected from battery and connected to a circuit consisting of two uncharged capacitors $C_2=3.0\mu F$ and $C_3=6.0\mu F$ through a switch (2) as shown in the figure. The sum of final charges on $C_2$ and $C_3$ is:

1. $40\mu C$
2. $36\mu C$
3. $54\mu C$
4. $20\mu C$

Q.

How do you define the potential difference between two points?

Q. The gap between the plates of a parallel plate capacitor of area $A$ and distance between plates$d$, is filled with a dielectric whose permittivity varies linearly from ${\in }^1$ at one plate to ${\in }^2$ at the other. The capacitance of capacitor is:

1. ${\in }_0({\in }_1+{\in }_2)A/d$
2. ${\in }_0({\in }_1+{\in }_2)A/2d$
3. ${\in }_{0}A/\left[d/n\left({\in }_2/{\in }_1\right)\right]$
4. ${\in }_0({\in }_1-{\in }_2)A/\left[d/n\left({\in }_2/{\in }_1\right)\right]$

Q.

a 80 microfarad capacitor is charged by 50V battery . d capacitor is disconnected from it and connected across uncharged 320 microfarad capacitor calculate the charge on second capacitor

Q.

Capacitor _________ dc flowing through it.

Q. The magnitude of induced electromotive force in the secondary coil depends on:

1. Ratio of the number of turns in the secondary coil to the number of turns in the primary coil.
2. Ratio of the number of turns in the primary coil to the number of turns in the secondary.
3. The magnitude of induced electromotive force in the primary coil.
4. Both A and C