All STD 12 - Current electricity questions
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- 151. Given below are two statements: Statement \(I\) : A uniform wire of resistance \(80\,\Omega\) is cut into four equal parts. These parts are now connected in parallel. The equivalent resistance of the combination will be \(5\,\Omega\). Statement \(II :\) Two resistance \(2\,R\) and \(3\,R\) are connected in parallel in a electric circuit. The value of thermal energy developed in \(3\,R\) and \(2\,R\) will be in the ratio \(3:2.\) In the light of the above statements, choose the most appropriate answer from the options given below 2022 Medium
- 152. In a potentiometer arrangement, a cell gives a balancing point at \(75\, cm\) length of wire. This cell is now replaced by another cell of unknown emf. If the ratio of the emf's of two cells respectively is \(3: 2\), the difference in the balancing length of the potentiometer wire in above two cases will be.........\(cm .\) 2022 Medium
- 153. In a potentiometer arrangement, a cell of emf \(1.20\, V\) gives a balance point at \(36\, cm\) length of wire. This cell is now replaced by another cell of emf \(1.80\, V\). The difference in balancing length of potentiometer wire in above conditions will be \(....cm\). 2022 Hard
- 154. In meter bridge experiment for measuring unknown resistance ' \(S\) ', the null point is obtained at a distance \(30 cm\) from the left side as shown at point \(D\). If \(R\) is \(5.6 k \Omega\), then the value of unknown resistance ' \(S\) ' will be \(\Omega .\)
2022 Medium - 155. In the given circuit ' \(a\) ' is an arbitrary constant. The value of \(m\) for which the equivalent circuit resistance is minimum, will be \(\sqrt{\frac{ x }{2}}\). The value of \(x\) is ...........
2022 Hard - 156. In the given figure of meter bridge experiment, the balancing length \(AC\) corresponding to null deflection of the galvanometer is \(40\,cm\). The balancing length, if the radius of the wire \(AB\) is doubled, will be \(....cm\)
2022 Medium - 157. In the given figure, the value of \(V_{0}\) will be \(.....V\).
2022 Hard - 158. Resistance are connected in a meter bridge circuit as shown in the figure. The balancing length \(l_{1}\) is \(40\,cm\). Now an unknown resistance \(x\) is connected in series with \(P\) and new balancing length is found to be \(80\,cm\) measured from the same end. Then the value of \(x\) will be \(.......\Omega\)
2022 Hard - 159. Resistance of the wire is measured as \(2\,\Omega\) and \(3\,\Omega\) at \(10^{\circ}C\) and \(30^{\circ}C\) respectively. Temperature cocoefficient of resistance of the material of the wire is............\(^{\circ}C ^{-1}\) 2022 Medium
- 160. The combination of two identical cells, whether connected in series or parallel combination provides the same current through an external resistance of \(2 \,\Omega\). The value of internal resistance of each cell is ............ \(\Omega\) 2022 Medium
- 161. The current density in a cylindrical wire of radius \(4 \; mm\) is \(4 \times 10^{6} \; Am ^{-2}\). The current through the outer portion of the wire between radial distance \(\frac{R}{2}\) and \(R\) is \(\dots \; \pi A .\) 2022 Medium
- 162. The current density in a cylindrical wire of radius \(r=4.0 \,mm\) is \(1.0 \times 10^{6} \,A / m ^{2}\). The current through the outer portion of the wire between radial distances \(r / 2\) and \(r\) is \(x \pi A\); where \(x\) is .......... 2022 Hard
- 163. The current \(I\) flowing through the given circuit will be \(.....A\).
2022 Medium - 164. The current \(I\) in the given circuit will be \(......A\)
2022 Medium - 165. The equivalent resistance between points \(A\) and \(B\) in the given network is ............ \(\Omega\)
2022 Medium - 166. The length of a given cylindrical wire is increased to double of its original length. The percentage increase in the resistance of the wire will be..... \(\%\). 2022 Medium
- 167. The total current supplied to the circuit as shown in figure by the \(5 V\) battery is \(A\)
2022 Medium - 168. The variation of applied potential and current flowing through a given wire is shown in figure. The length of wire is \(31.4 \,cm\). The diameter of wire is measured as \(2.4 \,cm\). The resistivity of the given wire is measured as \(x \times 10^{-3} \,\Omega cm\). The value of \(x\) is_______ [Take \(\pi=3.14]\)
2022 Medium - 169. Two cells of same emf but different internal resistances \(I_{1}\) and \(I_{2}\) are connected in series with a resistance \(R\). The value of resistance \(R\), for which the potential difference across second cell is zero, is 2022 Medium
- 170. Two coils require \(20\) minutes and \(60\) minutes respectively to produce same amount of heat energy when connected separately to the same source. If they are connected in parallel arrangement to the same source; the time required to produce same amount of heat by the combination of coils, will be________ \(min\) 2022 Hard
- 171. Two identical cells each of emf \(1.5 \,V\) are connected in parallel across a parallel combination voltmeter connected in the circuit measures \(1.2 \,V\). The internal resistance of each cell is.................\(\Omega\) 2022 Hard
- 172. Two resistors are connected in series across a battery as shown in figure. If a voltmeter of resistance \(2000 \,\Omega\) is used to measure the potential difference across \(500 \,\Omega\) resister, the reading of the voltmeter will be ............... \(V\)
2022 Medium - 173. Water fall from a \(40\,m\) high dam at the rate of \(9 \times 10^{4}\,kg\) per \(hour\). Fifty percentage of gravitational potential energy can be converted into electrical energy. Using this hydroelectric energy number of \(100\,W\) lamps, that can be lit, is (Take \(\left.g=10\,ms ^{-2}\right)\) 2022 Medium
- 174. What will be the most suitable combination of three resistors \(A =2\, \Omega, B =4\, \Omega, C =6\, \Omega\) so that \(\left(\frac{22}{3}\right)\Omega\) is equivalent resistance of combination\(?\) 2022 Medium
- 175. A \(16\, \Omega\) wire is bend to form a square loop. A \(9 \,{V}\) supply having internal resistance of \(1 \,\Omega\) is connected across one of its sides. The potential drop across the diagonals of the square loop is \(.......\,\times 10^{-1} \,{V}\) 2021 Medium
- 176. A capacitor of \(50 \,\mu {F}\) is connected in a circuit as shown in figure. The charge on the upper plate of the capacitor is \(......\,\mu {C} .\)
2021 Medium - 177. A cell \(E _{1}\) of \(emf 6 V\) and internal resistance \(2 \Omega\) is connected with another cell \(E _{2}\) of \(emf 4 V\) and internal resistance \(8 \Omega\) (as shown in the figure). The potential difference across points \(X\) and \(Y\) is............ \(V\)
2021 Hard - 178. A conducting wire of length \( l\) area of cross-section \(A\) and electric resistivity \(\rho\) is connected between the terminals of a battery. \(A\) potential difference \(V\) is developed between its ends, causing an electric current.If the length of the wire of the same material is doubled and the area of cross-section is halved, the resultant current would be 2021 Medium
- 179. A Copper \((Cu)\) rod of length \(25\, {cm}\) and cross- sectional area \(3\, {mm}^{2}\) is joined with a similar Aluminium \((Al)\) rod as shown in figure. Find the resistance of the combination between the ends \(A\) and \(B\) (in \({m} \Omega\)) (Take Resistivity of Copper \(=1.7 \times 10^{-8}\, \Omega \,{m}\), Resistivity of Aluminium \(=2.6 \times 10^{-8}\, \Omega \,{m}\) )
2021 Hard - 180. A current of \(10\, A\) exists in a wire of crosssectional area of \(5\, mm ^{2}\) with a drift velocity of \(2 \times 10^{-3}\, ms ^{-1}\). The number of free electrons in each cubic meter of the wire is .......... 2021 Medium
- 181. A current of \(5\; {A}\) is passing through a non-linear magnesium wire of cross-section \(0.04\; {m}^{2}\). At every point the direction of current density is at an angle of \(60^{\circ}\) with the unit vector of area of cross-section. The magnitude of electric field at every point of the conductor is ....\({V} / {m}\) (Resistivity of magnesium is \(\rho=44 \times 10^{-8}\, \Omega m\)) 2021 Hard
- 182. A current of \(6\, A\) enters one corner \(P\) of an equilateral triangle \(PQR\) having \(3\) wires of resistance \(2 \,\Omega\) each and leaves by the corner \(R\). The currents \(i_{1}\) in ampere is ........ .
2021 Hard - 183. A current through a wire depends on time as \(i =\alpha_{0} t +\beta t ^{2}\) where \(\alpha_{0}=20 A / s\) and \(\beta=8 As ^{-2} .\) Find the charge crossed through a section of the wire in \(15 \,s\) (in \(C\)) 2021 Medium
- 184. A cylindrical wire of radius \(0.5 \,mm\) and conductivity \(5 \times 10^{7}\, S / m\) is subjected to an electric field of \(10 \,mV / m .\) The expected value of current in the wire will be \(x ^{3} \,\pi mA\). The value of \(x\) is ...... 2021 Medium
- 185. A resistor develops \(500\, J\) of thermal energy in \(20 \,s\) when a current of \(1.5\, A\) is passed through it. If the current is increased from \(1.5 \,A\) to \(3\, A\) what will be the energy (in \(J\)) developed in \(20\, s\). 2021 Medium
- 186. A resistor dissipates \(192\, {J}\) of energy in \(1\, {s}\) when a current of \(4\, {A}\) is passed through it. Now, when the current is doubled, the amount of thermal energy dissipated in \(5 \,{s}\) in \(.....\,J.\) 2021 Medium
- 187. A square shaped wire with resistance of each side \(3\, \Omega\) is bent to form a complete circle. The resistance between two diametrically opposite points of the circle in unit of \(\Omega\) will be ...... 2021 Medium
- 188. A uniform heating wire of resistance \(36\, \Omega\) is connected across a potential difference of \(240\, {V}\) The wire is then cut into half and potential difference of \(240\, {V}\) is applied across each half separately. The ratio of power dissipation in first case to the total power dissipation in the second case would be \(1: {x}\), where \({x}\) is........... . 2021 Medium
- 189. A wire of \(1 \,\Omega\) has a length of \(1\, m\). It is stetched till its length increases by \(25\, \%\). The percentage change in resistance to the neartest integer is .....\(\%\) 2021 Hard
- 190. An electric bulb of \(500 \,watt\) at \(100\, volt\) is used in a circuit having a \(200\, {V}\) supply. Calculate the resistance \({R}\) to be connected in series with the bulb so that the power delivered by the bulb is \(500\, {W}\). (in \(\Omega\)) 2021 Medium
- 191. An electric bulb rated as \(200\, {W}\) at \(100 \,{V}\) is used in a circuit having \(200\, {V}\) supply. The resistance \('R'\) that must be put in series with the bulb so that the bulb delivers the same power is \(.....\,\Omega\) 2021 Medium
- 192. Consider a \(72\, cm\) long wire \(AB\) as shown in the figure. The galvanometer jockey is placed at \(P\) on \(A B\) at a distance \(x cm\) from \(A\). The galvanometer shows zero deflection. The value of \(x,\) to the nearest integer, is ..... \(cm\)
2021 Medium - 193. Consider an electrical circuit containing a two way switch \(^{\prime}{S}^{\prime}\). Initially \({S}\) is open and then \({T}_{1}\) is connected to \({T}_{2} .\) As the current in \({R}=6 \,\Omega\) attains a maximum value of steady state level, \({T}_{1}\) is disconnected from \({T}_{2}\) and immediately connected to \({T}_{3} .\) Potential drop across \({r}=3\, \Omega\) resistor immediately after \(T_{1}\) is connected to \(T_{3}\) is \(....\,V.\) (Round off to the Nearest Integer)
2021 Hard - 194. First, a set of \({n}\) equal resistors of \(10\; \Omega\) each are connected in series to a battery of emf \(20\; {V}\) and internal resistance \(10\; \Omega .\) A current \(I\) is observed to flow. Then, the \(n\) resistors are connected in parallel to the same battery. It is observed that the current is increased \(20\) times, then the value of \(n\) is .... . 2021 Hard
- 195. Five equal resistances are connected in a network as shown in figure. The net resistance between the points \(A\) and \(B\) is
2021 Medium - 196. Five identical cells each of internal resistance \(1\, \Omega\) and \(emf \;5\, {V}\) are connected in series and in parallel with an external resistance \('R'.\) For what value of \('R',\) current in series and parallel combination will remain the same ? (in \(\Omega\)) 2021 Hard
- 197. For the circuit shown, the value of current at time \({t}=3.2\, {s}\) will be ...... \({A}\). [Voltage distribution \(V(t)\) is shown by Fig. \((1)\) and the circuit is shown in Fig. \((2)\)]
2021 Hard - 198. In an electric circuit, a cell of certain emf provides a potential difference of \(1.25\, {V}\) across a load resistance of \(5\, \Omega .\) However, it provides a potential difference of \(1\, {V}\) across a load resistance of \(2\, \Omega\). The \(emf\) of the cell is given by \(\frac{x}{10} v\). Then the value of \(x\) is ..... . 2021 Medium
- 199. In the experiment of \(Ohm's law,\) a potential difference of \(5.0\, V\) is applied across the end of a conductor of length \(10.0\, cm\) and diameter of \(5.00\, mm .\) The measured current in the conductor is \(2.00\, A\). The maximum permissible percentage error in the resistivity of the conductor is 2021 Hard
- 200. In the figure given, the electric current flowing through the \(5\, k \Omega\) resistor is \('x' mA.\) The value of \(x\) to the nearest integer is .........
2021 Medium
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