Q. A capacitor is charged up to a potneital $V_{0}$. It is then connected to a resistance $R$ and a battery of emf $E$. Two possible graphs of potential difference across capacitor with time are shown. What is the most reasonable explanation of these graphs?

Current Electricity Report Error

A

The first graph shows what happens when the capacitor has potential difference less than $E$ initially and the second shows what happens when it has potential difference greater than $E$ initially:

B

The first graph shows what happens when the capacitors has potential difference greater than $E$ initially and the second shows what happens when it has a less than $E$ potential initially.

C

The first graph is the correct qualitative shape for any initial potential across capacitor, but the second is not possible

D

The second graph is the correct qualitative shape for any initial potential difference across capacitor, but the first is not possible.

Solution:

If initial potential difference across capacitor is less than battery EMF then battery will supply more charge to the capacitor and its potential difference increases and if initial potential difference across capacitor is greater than battery EMF then charge from capacitor flows into the battery and its potential difference decreases.

Questions from Current Electricity

1. The current of a conductor flowing through a conductor in terms of the drift speed of electrons is (the symbols have their usual meanings)

NTA Abhyas 2020

2. The diagrams show five different ways in which currents $i_{1}, i_{2}, i_{3}$ can combine at a junction.

For which of these junctions, is the following equation correct ?
$i_{1}+i_{2}=i_{3}+i_{4}$

3. Two sources of equal emf are connected to an external resistance $R$. The internal resistances of the two sources are $R_1$ and $R_2 (R_2 > R_1).$ If the potential difference across the source having internal resistance $R_2$, is zero, then :

AIEEE 2005

4. Two voltameters, one of copper and another of silver, are joined in parallel. When a total charge $q$ flows through the voltameters, equal amount of metals are deposited. If the electrochemical equivalents of copper and silver are $Z_1$ and $Z_2$ respectively, the charge which flows through the silver voltameter is :

AIEEE 2005

5. The thermo emf of a thermocouple varies with the temperature $θ$ of the hot junction as $E = a \,θ + bθ^2$ in volts where the ratio $a/b$ is $700^{\circ}C$. If the cold junction is kept at $0^{\circ}C$, then the neutral temperature is

AIEEE 2004

Physics Most Viewed Questions

1. A car starts from rest and accelerates at $5\, m / s ^{2}$ At $t=4\, s$, a ball is dropped out of a window by a person sitting in the car. What is the velocity and acceleration of the ball at $t =6\, s$ ? (Take $\left. g =10\, m / s ^{2}\right)$

NEET 2021 Motion in a Straight Line

2. If $E$ and $G$ respectively denote energy and gravitational constant, then $\frac{ E }{ G }$ has the dimensions of:

NEET 2021 Physical World, Units and Measurements

3. The de Broglie wavelength of an electron moving with kinetic energy of $144 \,eV$ is nearly

NEET 2020 Dual Nature of Radiation and Matter

4. A wheel with $20$ metallic spokes each $1\, m$ long is rotated with a speed of $120\, rpm$ in a plane perpendicular to a magnetic field of $0.4\, G$. The induced emf between the axle and rim of the wheel will be, $(1 G = 10^{-4}\, T)$

NEET 2020 Electromagnetic Induction

5. Calculate the acceleration of the block and trolly system shown in the figure The coefficient of kinetic friction between the trolly and the surface is $0.05. (g = 10 \,m/s^{2}$, mass of the string is negligible and no other friction exists

NEET 2020 Laws of Motion