JEE Main Physics - Capacitance
Exam Duration: 60 Mins Total Questions : 25
Three identical capacitors are connected together differently. For the same voltage to every combination, the one that stores maximum energy is
- (a)
the three in series
- (b)
the three in parallel
- (c)
two in series with the third in parallel with it
- (d)
two in parallel with the third in series with it
Two condensers of capacities 2C and C are joined in parallel and charged upto potential V. The battery is removed and the condenser of capacity C is filled completely with a medium of dielectric constant K. The potential difference across the capacitors will now be
- (a)
\(\frac { 3V }{ K+2 } \)
- (b)
\(\frac { 3V }{ K}\)
- (c)
\(\frac { V }{ K+2 } \)
- (d)
\(\frac { V }{ K } \)
A capacitor with capacity 100 \(\mu F\) is charged with a battery of 24 V. It is then connected to a battery of 12 V with positive plate is joined to positive terminal of battery. Heat developed in the process of flow of charge after connection is
- (a)
greater than 7.2 mJ
- (b)
less than 7.2 mJ
- (c)
equal to 7.2 mJ
- (d)
No heat is produced
A capacitor is made of two circular plates of radius R each, separated by a distance d << R. The capacitors is connected to a constant voltage. A thin conducting disc of radius r << R and thickness t << r is placed at a centre of the bottom plate. Then, the minimum voltage required to lift the disc, if the mass of the disc is m, is
- (a)
\(\sqrt { \frac { mg{ d }^{ 2 } }{ \pi { \varepsilon }_{ 0 }{ r }^{ 2 } } } \)
- (b)
\(\frac { { \varepsilon }_{ 0 }\sigma }{ d } \)
- (c)
\(\frac { \sigma }{ { \varepsilon }_{ 0 } } d\)
- (d)
None of these
Match the value of capacitance given in Column I with their values given in Column II and select the correct option from the choices given below
Column I | Column II |
A. Capacitance of parallel plate capacitor in air | 1. \(\frac { K{ \varepsilon }_{ 0 }A }{ d } \) |
B. Capacitance of parallel plate capacitor when a dielectric slab is inserted partially between the plates | 2. \(\frac { { \varepsilon }_{ 0 }A }{ \left( d-t \right) +\frac { t }{ K } } \) |
C. Capacitance of parallel plate capacitor when a dielectric slab is inserted fully between the plates. | 3. \(\frac { { \varepsilon }_{ 0 }A }{ d } \) |
- (a)
A B C 1 2 3 - (b)
A B C 3 2 1 - (c)
A B C 3 2 1 - (d)
A B C 2 3 1
A parallel plate condenser with a dielectric of dielectric constant K between the plates has a capacity and is charged to a potential V volt. The dielectric slab is slowly removed from between the plates and then reinserted. The net work done by the system in this process is
- (a)
\(\frac { 1 }{ 2 } \left( K-1 \right) { CV }^{ 2 }\)
- (b)
\({ CV }^{ 2 }\left( K-1 \right) K\)
- (c)
\(\left( K-1 \right) { CV }^{ 2 }\)
- (d)
zero
A fully charged capacitor has a capacitance C. It is discharged through a small coil of resistance wire embedded in a thermally insulated block of specific heat capacity s and mass m. If the temperature of the block is raised by \(\triangle T\), the potential difference V across capacitance is
- (a)
\(\sqrt { \frac { 2mC\triangle T }{ s } } \)
- (b)
\(\frac { mC\triangle T }{ s } \)
- (c)
\(\frac { ms\triangle T }{ C } \)
- (d)
\(\sqrt { \frac { 2ms\triangle T }{ C } } \)