InterviewSolution
Saved Bookmarks
InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
In the fig. shown the circuit is in steady state. How long does it take for the capacitor to discharge until the potential difference across it becomes `1 V` ?A. `1766.1 mu s`B. `333.34 mu s`C. `1000 mu s`D. `333.34 s` |
|
Answer» Correct Answer - C `q=q_(0) e^(-t//tau) V=V_(0) e^(-t//tau) i=20 e^((-3t)/(1000))t=1000s`. |
|
| 152. |
In the fig. shown the circuit is in steady state. what is the potential difference across the capacitor in steady state ?A. 5 VB. 10 VC. 20 VD. 40 V |
|
Answer» Correct Answer - C In steady state capacitor is equivalent to open circuit `:. V_(C) = 20 V`. |
|
| 153. |
The time in seconds required to produce a `P.D` at `20 V` across a capacitor at `1000 mu F` when it is charged at the steady rate of `200mu C//sec` is.A. 50B. 100C. 150D. 200 |
|
Answer» Correct Answer - B `(dq)/(dt)=(c.dv)/(dt)`. |
|
| 154. |
In the circuit shown in figure. The charge on capacitor `C_(2)` in steady state is `10^(x) mu C`. Find the value of `x`. . |
|
Answer» Correct Answer - 1 Use the concept of CR-circuit. |
|
| 155. |
Equipotentials at a great distance from a collection of charges whose total sum is not zero are approximatelyA. spheresB. planesC. paraboloidsD. ellipsoids |
|
Answer» Correct Answer - A Collection of charges whose total sum is not zero can be considered as a point charge from a great distance. So, equipotentials should be spheres. |
|
| 156. |
A parallel plate capacitor is connected across a source of covstant potential difference. If a dielectric slab is introduced between the two plates, thenA. Charge on capacitor increasesB. Some charge from the capacitor will flow back into the sourceC. He electric field between the plates will decreaseD. The electric field between the plates will not change |
|
Answer» Correct Answer - A::D |
|
| 157. |
The radii of two metallic spheres are 5 cm and 10 cm and both carry equal charge of `75 mu C`. If the two spheres are shorted then charge will be transferred-A. `25mu C` from smaller to biggerB. `25 mu C` from bigger to smallerC. `50 mu C` from smaller to biggerD. `50 mu C ` from bigger to smaller |
| Answer» Correct Answer - A | |
| 158. |
Two spheres of radii `12 cm` and `16 cm` have equal charge. The radii of their energies is.A. `3 : 4`B. `4 : 3`C. `1 : 2`D. `2 : 1` |
|
Answer» Correct Answer - B `U =(q^(2))/(2C), U alpha (1)/( r)`. |
|
| 159. |
`n` Capacitors of `2 mu F` each are connected in parallel and a `p.d` of `200 V` is applied to the combination. The total charge on them was `1c` then `n` is equal to.A. 3333B. 3000C. 2500D. 25 |
|
Answer» Correct Answer - C `Q = nCV`. |
|
| 160. |
Two capacitors of capacites `1 mu F` and `C mu F` are connected in series and the combination is charged to a potential difference of `120 V`. If the charge on the combination is `80 muC`, the energy stored in the capacitor `C` in micro joules is :A. 1800B. 1600C. 14400D. 7200 |
|
Answer» Correct Answer - B `C_(1)V_(1) = C_(2)V_(2)`. |
|
| 161. |
Three capacitors of `3 mu F,2 mu F` and `6 mu F` are connected in series. When a battery of `10 V` is connected to this combination then charge on `3 mu F` capacitor will be.A. `5 mu C`B. `10 mu C`C. `15 mu C`D. `20 mu C` |
|
Answer» Correct Answer - B In series charge constant `Q = C_(eff) V`. |
|
| 162. |
A parallel plate air capacitor is connected to a battery. After charging fully, the battery is disconnected and the plates are pnlled apart to increase their separation. Which of the following statements is correct ?A. The electric field between the plates of capacitor decreasesB. The electric field between the plates of capacitor increasesC. The electric field between the plates of capacitor remains sameD. Potential difference between the plates remains the same |
|
Answer» Correct Answer - C |
|
| 163. |
Two identical capacitors are connected in series with a source of constant voltage `V`. If `Q` is the charge on one of the capacitors, the capacitance of each capacitor is :A. `Q//2V`B. `Q//V`C. `2Q//V`D. None of these |
|
Answer» Correct Answer - C |
|
| 164. |
For the three circuit shown in figure- across the battery capacitors are connected in some combination. Which of the following is the correct order of combination : A. series, series, parallefB. series, parallel, parallelC. parallel, series, parallelD. none |
|
Answer» Correct Answer - B |
|
| 165. |
Four capacitors and two batteries are connected as shown in the figure. The potential difference between the points `a` and `b` is: A. `0V`B. `13V`C. `17V`D. `27V` |
|
Answer» Correct Answer - C |
|
| 166. |
Four capacitors and two batteries are connected as shown in the diagram. The `p.d` between the points `a` and `b` is .A. 22 VB. 15 VC. 13 VD. 0 V |
|
Answer» Correct Answer - C P.D across `2mu F` capacitor is `(22-7) xx (3)/((3+2))=9V` p.d across `8 muF` capacitor is `= 22V` As the positively charged plates of `2 muF` and `8 muF` are connected `V_(a)-V_(b) = 22-9 = 13 V`. |
|
| 167. |
In the adjoining diagram, the condenser `C` will be fully charged to potential `V` if .A. `S_(1)` and `S_(2)` both are openB. `S_(1)` and `S_(2)` both are closedC. `S_(1)` is closed and `S_(2)` is openD. `S_(1)` is open and `S_(2)` is closed. |
|
Answer» Correct Answer - C If `S_(1)` and `S_(2)` both are closed then charge and discharge processes with simoultaneously take place. Hence to charge to condenser fully the key `S_(1)` must be closed and `S_(2)` must remain open. |
|
| 168. |
A circuit is shown in figure. Find the charge on the condenser having a capacity of `5muF` in steady state. |
|
Answer» Correct Answer - `9muC` |
|
| 169. |
The charge on the condenser of capacitance `2mu F` in the following circuit will be - A. `4.5 mu C`B. `6.5 mu C`C. `7 mu C`D. `30 mu C` |
| Answer» Correct Answer - B | |
| 170. |
In the adjoining diagram, the condenser `C` will be fully charged to potential `V` if .A. `S_(1)` and `S_(2)` both are openB. `S_(1)` and `S_(2)` both are closedC. `S_(1)` is closed and `S_(2)` is openD. `S_(1)` is open and `S_(2)` is closed. |
| Answer» Correct Answer - C | |
| 171. |
A capacitor is made ofa flat plate of area `A` and another plate is bent at four points and placed above the flat plate as shown in figure. Dimension ofboth the plates are shown in figure. Find the capacitance of this structure between the two plates. |
|
Answer» Correct Answer - `(11 epsilon_(0)A)/(18d)` |
|
| 172. |
A parallel plate capacitor of capacitance C is connected to a battery and is charged to a potential difference V. Another capacitor of capacitance 2C is ismilarly charged to a potential difference 2V. The charging battery is now disconnected and the capacitors are connected in parallel to each other in such a way that the poistive terminal of one is connected to the negative terminal of the other. The final energy of the configuration isA. zeroB. `(25CV^(2))/(6)`C. `(3CV^(2))/(2)`D. `(9CV^(2))/(2)` |
| Answer» Correct Answer - C | |
| 173. |
A parallel plate capacitor of capacitance C is connected to a battery and is charged to a potential difference V. Another capacitor of capacitance 2C is ismilarly charged to a potential difference 2V. The charging battery is now disconnected and the capacitors are connected in parallel to each other in such a way that the poistive terminal of one is connected to the negative terminal of the other. The final energy of the configuration isA. zeroB. `(3)/(2) CV^(2)`C. `(25)/(6) CV^(2)`D. `(9)/(2) CV^(2)` |
|
Answer» Correct Answer - B `U=(1)/(2)CV^(2)=(1)/(2)(3C)V^(2)=(3)/(2)CV^(2)`. |
|
| 174. |
A parallel plate capacitor of capacitance C is connected to a battery and is charged to a potential difference V. Another capacitor of capacitance 2C is ismilarly charged to a potential difference 2V. The charging battery is now disconnected and the capacitors are connected in parallel to each other in such a way that the poistive terminal of one is connected to the negative terminal of the other. The final energy of the configuration isA. zeroB. `(3)/(2) CV^(2)`C. `(35)/(6) CV^(2)`D. `(9)/(2) CV^(2)` |
|
Answer» Correct Answer - B Net charge `Q =Q_(2)-Q_(1)` potential is `V_(l)` `:. V_(1)=((C_(0))/(C+C_(0)))V_(0)` Similarly after nth operation , `E = 1//2C^(1) V^(2)`. |
|
| 175. |
For the circuit shown in figure, which of the following statements is true ? A. With `S_(1)` closed `V_(1) = 15 V,V_(2) = 20 V`B. With `S_(3)` closed `V_(1) = V_(2) = 25 V`C. With `S_(1)` and `S_(2)` closed `V_(1) =V_(2) = 0`D. With `S_(3)` closed `V_(1) = 30 V,V_(2) = 20 V` |
|
Answer» Correct Answer - D When `S_(3)` is closed, both capacitors attain common potential which is average of the two. |
|
| 176. |
A capacitor of capacitance `10 m F` is charged up a potential difference of `2V` and then the cell is removed. Now it is connected to a cell of `emf 4V` and is charged fully. In both cases the polarities of the two cells are in the same directions. Total heat produced in the second charging process is :A. 10 mJB. 20 mJC. 40 mJD. 80 mJ |
|
Answer» Correct Answer - B Energy stored in capacitor when it is charged upto `2V = (1)/(2) 10 2^(2) = 20 mu J = u_(1)` (suppose) Energy stored in capacitor when it is charged upto `4V =(1)/(2) 10 4^(2) = 80 mu J = u_(2)` (suppose) Increase in charge `= 40 + 20 = 20 mu C` Energy drawn from cell `= 20 xx 4 = 80 mu J = u` (suppose) Heat produced `d =u_(1) + u-u_(2)` `=20 +80 - 80 = 20 muJ`. |
|
| 177. |
A parallel plate condenser with plate separation d is charged with the help of a battery so that `U_(0)` energy is stored in the system. A plate of dielectric constant K and thickness d is placed between the plates of condenser while battery remains connected. The new energy of the system will be-A. `KU_(0)`B. `K^(2)U_(0)`C. `(U_(0))/(K)`D. `(U_(0))/(K^(2))` |
| Answer» Correct Answer - A | |
| 178. |
Two identical planar capacitor connected in parallel and charged to a voltage `U_(0)=12V`. When you disconnect them from the voltage source, the distance between the plates of one of the capacitors is reduced to one third of the original distance. What will be the new voltage on the capacitors ? |
|
Answer» Correct Answer - 6V |
|
| 179. |
A capacitor of capacity `C_(0)` is charged to certain potential and enrgy stored in it is `U_(0)`. Now this capacitor is connected in parrallel to uncharged capacitor of capacitance. `C`. Find the loss of energy. |
|
Answer» `U_(0)=(1)/(2)C_(0)V_(0)^(2) C_(0)V_(0)^(2)` `DeltaU=(1)/(2)(C_(1)C_(2))/(C_(1)+C_(2))(VG_(1)-V_(2))^(2)` `=(1)/(2)(C-(0)C)/((C_(0)+C))(V_(0)-0)^(2)=((c)/(C_(0)+C))((1)/(2)C_(0)V_(0)^(2))` `=(CU_(0))/(C_(0)+C)` |
|
| 180. |
A 3 mega ohm resistor and an uncharged `1 mu F` capacitor are connected in a single loop circuit with a constant source of 4 volt. At one second after the connection is made what are the rates at which, (i) The charge on the capacitor is increasing.A. `4(1-e^(-1//3))mu C//s`B. `4e^(-1//3) mu C//s`C. `(4)/(3)e^(-1//3) mu C//s`D. `(4)/(3)(1-e^(-1//3)) mu C//s` |
| Answer» Correct Answer - C | |
| 181. |
How does the total energy stored in the capacitors in the circuit shown in the figure change when first switch `K_(1)` is closed (process-1) and then switch `K_(2)` is also closed (process-2), Assume that all capacitor were initially uncharged? A. Increases in process-1B. Increases in process-2C. Decreases in process-2D. Magnitude of change in process-2 is less than that inprocess -1 |
|
Answer» Correct Answer - A::B::D |
|
| 182. |
The plates of capacitor of capacitance `10 mu F`, charged to `60 mu C`, are joined together by a wire of resistance `10 Omega` at t = 0, then (i) the charge on the capacitor in the circuit at t=0 is :A. `120 mu C`B. `60 mu C`C. `30 mu C`D. `44 mu C` |
| Answer» Correct Answer - B | |
| 183. |
A 3 mega ohm resistor and an uncharged `1 mu F` capacitor are connected in a single loop circuit with a constant source of 4 volt. At one second after the connection is made what are the rates at which, (iv) Energy is being delivered by the source.A. `16(1-e^(-1//3))mu J//s`B. `16 mu J//s`C. `(16)/(3) e^(-1//3) mu J//s`D. `(16)/(3) (1-e^(-1//3)) mu J//s` |
| Answer» Correct Answer - C | |
| 184. |
The charge on each of the capacitors 0.16 ms after the switch S is closed in figure is : A. `24 mu C`B. `26.8 mu C`C. `25.2 mu C`D. `40 mu C` |
| Answer» Correct Answer - C | |
| 185. |
An uncharged capacitor of capacitance `8.0 mu F` is connected to a battery of emf 6.0 V through a resistance of `24 Omega`, then (ii) The current in the circuit at one time constant after the connections are made is :A. 0.25 AB. 0.09 AC. 0.4 AD. `0 A` |
| Answer» Correct Answer - B | |
| 186. |
An uncharged capacitor of capacitance `8.0 mu F` is connected to a battery of emf 6.0 V through a resistance of `24 Omega`, then (i) The current in the circuit just after the connections are made is :A. 0.25 AB. 0.5 AC. 0.4 AD. `0 A` |
| Answer» Correct Answer - A | |
| 187. |
An uncharged capacitor of capacitance `100 mu F` is connected to a battery of emf 20V at t = 0 through a resistance `10 Omega`, then (i) the maximum rate at which energy is stored in the capacitor is :A. 10 J/sB. 20 J/sC. 40 J/sD. 5 J/s |
| Answer» Correct Answer - A | |
| 188. |
An uncharged capacitor of capacitance `100 mu F` is connected to a battery of emf 20V at t = 0 through a resistance `10 Omega`, then (i) the maximum rate at which energy is stored in the capacitor is :A. (4 ln 2) msB. (2 in 2) msC. (in 2) msD. (3 ln 2) ms |
| Answer» Correct Answer - C | |
| 189. |
A battery of `20V` is connected to a capacitor of capacitance `10 muF`. Now battery is removed and this capacitor is connected to a second uncharged capacitor. If the charge distributes equally on these two capacitors, the total energy stored in the two capacitors will beA. `250muJ`B. `500muJ`C. `750muJ`D. `1000muJ` |
|
Answer» Correct Answer - D Since final charges are same, potential is same i.e., `C_(1)=C_(2)=10muF` `V=(10xx20+10xx0)/(10+10)=10V` `U_(f)=(1)/(2)(C_(1)+C_(2))V^(2)=(1)/(2)(10+10)(10)^(2)xx10^(-6)` `=1000muJ` |
|
| 190. |
To form a composite `16 muF, 100 V` capacitor from a supply of identical capacitors market `8 muF, 250 V`, we require a minimum number of capacitorsA. 2B. 8C. 16D. 32 |
|
Answer» Correct Answer - D |
|
| 191. |
Two capacitors `C_(1) = 2 muF` and `C_(2) = 6 muF` in series, are connected in parallel to a third capacitor `C_(3) = 4 muF`. This arrangement is then connected to a battery of e.m.f `= 2V`, as shown in the figure. How much energy is lost by the battery in charging the capacitors A. `22 xx 10^(-6) J`B. `11 xx 10^(-6) J`C. `((32)/(2)) xx 10^(-6) J`D. `((16)/(3)) xx10^(-6) J` |
|
Answer» Correct Answer - B `E_(lost)=(1)/(2)C_(eff)V^(2)`. |
|
| 192. |
Given a number of capacitors labelled as `C,V`. Find the minimum number of capacitors needed to get an arrangement equivalent to `C_(net),V_(net)`.A. `n=(C_("net"))/(C) xx(V_("net")^(2))/(V^(2))`B. `n=(C)/(C_("net"))xx(V^(2))/(V_("net")^(2))`C. `n=(C)/(C_("net"))xx(V)/(V_("net"))`D. `n=(C_("net"))/(C)xx(V_("net"))/(V)` |
|
Answer» Correct Answer - A `F=(sigma Q)/(2 epsilon_(0))=(Q^(2))/(2 epsilon_(0)A)`. |
|
| 193. |
Find the equivalent capacitance across `A` and `B` for the arrangement shown in figure. All the capacitors are of capacitance `C` `A. `(3C)/14`B. `C/8`C. `(3C)/16`D. None of these |
|
Answer» Correct Answer - A |
|
| 194. |
A parallel plate capacitor of plate area A and plate separation d is charged to potential difference V and then the battery is disconnected. A slab of dielectric constant K is then inserted between the plates of the capacitor so as to fill the space between the plates. If Q, E and W denote respectively, the magnitude of charge on each plate, the electric field between the plates (after the slab is inserted), and work done on the system, in question, in the process of inserting the slab, thenA. `Q=(epsilon_(0)AV)/(d)`B. `Q=(epsilon_(0)KAV)/(d)`C. `E = (V)/(Kd)`D. `W =- (epsilon_(0)AV^(2))/(2d) (1-(1)/(K))` |
|
Answer» Correct Answer - A::C::D `C = (in_(0)A)/(d), Q = CV rArr (in_(0)A)/(d)V` Since battery is disconnected after charging so `Q` becomes constant `(A) Q = (in_(0)A)/(d)V` `(C )E = (V)/(Kd)` `(D) U_(i) = (1)/(2)CV^(2), & U_(f) = (1)/(2)KC ((V)/(K))^(2)` `DeltaW = U_(f) - U_(i) =-(1)/(2)Cv^(2) (1-(1)/(K))` `= (1)/(2) ((in_(0)A)/(d)V^(2)) (1-(1)/(K))` |
|
| 195. |
If there are n capacitors in parallel connected to V volt source, then the energy stored is equal toA. `(1)/(2)n CV^(2)`B. `(1)/(2)(CV^(2))/(n)`C. `(1)/(2)CV^(2)`D. none of these |
|
Answer» Correct Answer - B Energy stored by an system of capacitors `i` `= (1)/(2)C_("net") V^(2)` where `V` is source voltage Thus, `n` capacitors are connected in parallel, Therefore `C_("net") = nC` `:. E_("net") = (1)/(2)nCV^(2)` |
|
| 196. |
STATEMENT-1: A parallel plate capacitor is charged by a battery. The battery is then disconnected. If the distance the plates is increased, the enegry strored in the capacitor will decrease. STATEMENT-2: Work has to be done to increase the separation between the plates of a charged capacitor.A. Statement -1 si Ture, Statement -2 is True, Statement -2 is a correct explanation for Statement -1.B. Statement-1 is True, Statement-2 is True, Statement-2 is Not a correct explanation for Statement-1.C. Statement-1 is True, Statement-2 is False.D. Statement-1 is False, Statement-2 is True. |
|
Answer» Correct Answer - D The correct choice is `(D)`. The charge `Q` remains uncharged as the battery is disconnected. The capacitance `C` decreases if the separation between the plates s increased. Now, enegry stored `U = Q^(2)//2C`. Since `Q` remains the same and `C` is decreased, `U` will increases. |
|
| 197. |
STATEMENT-1: A parallel plate capacitor is charged by a battery of voltage `V`. The battery is then disconnected. If the space between the plates is filled with a dielectric, the enegry stroed in the capacitor will decrease STATEMENT-2: The capacitance of a capacitor increases due to the introduciton of a dielectric between the plates.A. Statement -1 si Ture, Statement -2 is True, Statement -2 is a correct explanation for Statement -1.B. Statement-1 is True, Statement-2 is True, Statement-2 is Not a correct explanation for Statement-1.C. Statement-1 is True, Statement-2 is False.D. Statement-1 is False, Statement-2 is True. |
|
Answer» Correct Answer - B The correct choice is `(B)`. The charge `Q` on the capacitor plates remains uncharged because there is no source to supply extra charge as the battery is disconnected. The capacitance `C` increases due to the introduction of the dielectric. Now, enegry stored `U = Q^(2)//2C`. Since `Q` remain uncharged and `C` increases, `U` will decreases. |
|
| 198. |
STATEMENT-1: A parallel plate capacitor is charged by a `d.c.` source supplying a constant voltage `V`. If the plates are kept connected to the source and the space between the plates is filled with a dielectric, the charge on the plates will increases. STATEMENT-2: Additional charge will flow from teh source to the plates.A. Statement -1 si Ture, Statement -2 is True, Statement -2 is a correct explanation for Statement -1.B. Statement-1 is True, Statement-2 is True, Statement-2 is Not a correct explanation for Statement-1.C. Statement-1 is True, Statement-2 is False.D. Statement-1 is False, Statement-2 is True. |
|
Answer» Correct Answer - A The correct choice is `(A)`. Since the source supplies a contant voltage `V`. The potential difference between the plates remains equal to `V` because the source is not disconnected. The capacitance `C` increases due to the introduction of the dielectric. since `Q = CV`, the charge `q` on the capacitor plates will increase. |
|
| 199. |
In the circuit in figure `emf E_(1) = 14V` (internal resistance `r_(1) = 1Omega`),`R_(1) = 6Omega R_(2) = 3.5 Omega, emf E_(2) = 12v` (internal resistance `r_(2) = 0.5Omega), C_(1) = 4muF` and `C_(2) = 2muF`. The potential difference across `R_(2)` isA. `10.5V`B. `12.5V`C. `15.0V`D. `26V` |
| Answer» Correct Answer - A | |
| 200. |
In the circuit in figure `emf E_(1) = 14V` (internal resistance `r_(1) = 1Omega`),`R_(1) = 6Omega R_(2) = 3.5 Omega, emf E_(2) = 12v` (internal resistance `r_(2) = 0.5Omega), C_(1) = 4muF` and `C_(2) = 2muF`. The effective capacitance of the circuit isA. `2muF`B. `2//3muF`C. `3muF`D. `4//3muF` |
| Answer» Correct Answer - D | |