All STD 12 - Current electricity questions
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- 201. In the given circuit of potentiometer, the potential difference \(E\) across \(AB\) ( \(10\, m\) length) is larger than \(E _{1}\) and \(E _{2}\) as well. For key \(K _{1}\) (closed), the jockey is adjusted to touch the wire at point \(J_{1}\) so that there is no deflection in the galvanometer. Now the first battery \(\left( E _{1}\right)\) is replaced by second battery \(\left( E _{2}\right)\) for working by making \(K _{1}\) open and \(K _{2}\) closed. The galvanometer gives then null deflection at \(J _{2}\). The value of \(\frac{ E _{1}}{ E _{2}}\) is \(\frac{ a }{ b },\) where \(a =\) ...............
2021 Medium - 202. In the given figure, a battery of emf \(E\) is connnected across a conductor \(P Q\) of length \('Y'\) and different area of cross-sections having radii \(r_{1}\) and \(r_{2}\left(r_{2}\,<\,r_{1}\right)\). Choose the correct option as one moves from \(P\) to \(Q\) :
2021 Hard - 203. In the given figure switches \(S_{1}\) and \(S_{2}\) are in open condition. The resistance across \(a b\) when the switches \(S_{1}\) and \(S_{2}\) are closed is \(...\,\Omega\)
2021 Hard - 204. In the given figure, the \(emf\) of the cell is \(2.2\, {V}\) and if internal resistance is \(0.6\, \Omega\). Calculate the power dissipated in the whole circuit: (in \(W\))
2021 Hard - 205. In the given figure, there is a circuit of potentiometer of length \(A B=10 \,{m}\). The resistance per unit length is \(0.1 \,\Omega\) per \({cm}\). Across \({AB}\), a battery of emf \({E}\) and internal resistance ' \({r}^{\prime}\) is connected. The maximum value of emf measured by this potentiometer is : (In \(V\))
2021 Medium - 206. In the given potentiometer circuit arrangement, the balancing length \({AC}\) is measured to be \(250\) \({cm}\). When the galvanometer connection is shifted from point \((1)\) to point \((2)\) in the given diagram, the balancing length becomes \(400\, {cm}\). The ratio of the emf of two cells, \(\frac{\varepsilon_{1}}{\varepsilon_{2}}\) is -
2021 Hard - 207. The colour coding on a carbon resistor is shown in the given figure. The resistance value of the given resistor is:
2021 Medium - 208. The energy dissipated by a resistor is \(10 \,mJ\) in \(1\,s\) when an electric current of \(2\, mA\) flows through it. The resistance is \(....... \Omega\) (Round off to the Nearest Integer) 2021 Easy
- 209. The equivalent resistance of the given circuit between the terminals \({A}\) and \({B}\) is \(....\Omega\)
2021 Hard - 210. The four arms of a Wheatstone bridge have resistances as shown in the figure. A galvanometer of \(15\, \Omega\) resistance is connected across \(BD\). Calculate the current through the galvanometer when a potential difference of \(10\, V\) is maintained across \(AC.\)
2021 Hard - 211. the given potentiometer has its wire of resistance \(10\, \Omega\). When the sliding contact is in the middle of the potentiometer wire, the potential drop across \(2\, \Omega\) resistor is -
2021 Hard - 212. The ratio of the equivalent resistance of the network (shown in figure) between the points \(a\) and \({b}\) when switch is open and switch is closed is \({x}: 8 .\) The value of \({x}\) is ..... .
2021 Hard - 213. The resistance of a conductor at \(15^{\circ} {C}\) is \(16\, \Omega\) and at \(100\, {C}\) is \(20\, \Omega\). What will be the temperature coefficient of resistance of the conductor? 2021 Medium
- 214. The value of current in the \(6 \,\Omega\) resistance is \(....\,A\)
2021 Hard - 215. The voltage across the \(10\, \Omega\) resistor in the given circuit is \(x\) volt. The value of \('x'\) to the nearest integer is..........
2021 Medium - 216. The voltage drop across \(15\, \Omega\) resistance in the given figure will be \(.....V.\)
2021 Hard - 217. Two cells of emf \(2\, E\) and \(E\) with internal resistance \(r _{1}\) and \(r _{2}\) respectively are connected in series to an external resistor \(R\) (see \(figure\)). The value of \(R ,\) at which the potential difference across the terminals of the first cell becomes zero is
2021 Hard - 218. Two wires of same length and thickness having specific resistances \(6\, \Omega \,cm\) and \(3 \,\Omega\, cm\) respectively are connected in parallel. The effective resistivity is \(\rho\, \Omega \,cm\). The value of \(\rho\) to the nearest integer, is ..... . 2021 Medium
- 219. What equal length of an iron wire and a copper-nickel alloy wire, each of \(2 \; {mm}\) diameter connected parallel to give an equivalent resistance of \(3 \Omega ?\) (Given resistivities of iron and copper-nickel alloy wire are \(12 \;\mu \Omega {cm}\) and \(51\; \mu \Omega {cm}\) respectively) (in \({m}\)) 2021 Hard
- 220. A battery of \(3.0\, V\) is connected to a resistor dissipating \(0.5\, W\) of power. If the terminal voltage of the battery is \(2.5\, V\) the power dissipated within the internal resistance is\(.......W\) 2020 Hard
- 221. A potentiometer wire \(PQ\) of \(1\,m\) length is connected to a standard cell \(E _{1}\). Another cell \(E _{2}\) of emf \(1.02\, V\) is connected with a resistance \('r'\) and switch \(S\) (as shown in figure). With switch \(S\) open, the null position is obtained at a distance of \(49\, cm\) from \(Q\). The potential gradient in the potentiometer wire is.......\(V/cm\)
2020 Medium - 222. An electrical power line, having a total resistance of \(2 \Omega\), delivers \(1 \,kW\) at \(220\, V\). The efficiency of the transmission line is approximately \(.......\%\) 2020 Medium
- 223. An ideal cell of emf \(10\, V\) is connected in circuit shown in figure. Each resistance is \(2\, \Omega .\) The potential difference (in \(V\)) across the capacitor when it is fully charged is
2020 Hard - 224. Consider four conducting materials copper, tungsten, mercury and aluminium with resistivity \(\rho_{ C }, \rho_{ T }, \rho_{ M }\) and \(\rho_{ A }\) espectively Then: 2020 Easy
- 225. Four resistances \(40 \ \Omega, 60\ \Omega, 90\ \Omega\) and \(110\ \Omega\) make the arms of a quadrilateral \(A,B,C,D\). Across \(AC\) is a battery of emf \(40\, V\) and internal resistance negligible. The potential difference across \(BD\) is \(V\) is......
2020 Medium - 226. Four resistances of \(15\; \Omega, 12\; \Omega, 4 \;\Omega\) and \(10\; \Omega\) respectively in cyclic order to form Wheats tone's network. The resistance that is to be connected in parallel with the resistance of \(10\; \Omega\) to balance the network is .................. \(\Omega\) 2020 Medium
- 227. In a building there are \(15\) bulbs of \(45\; \mathrm{W}, 15\) bulbs of \(100\; \mathrm{W}, 15\) small fans of \(10 \;\mathrm{W}\) and \(2\) heaters of \(1 \;\mathrm{kW}\). The voltage of electric main is \(220\; \mathrm{V}\). The minimum fuse capacity (rated value) of the building will be: .......... \(A\) 2020 Medium
- 228. In a meter bridge experiment \(\mathrm{S}\) is a standard resistance. \(\mathrm{R}\) is a resistance wire. It is found that balancing length is \(l=25 \;\mathrm{cm} .\) If \(\mathrm{R}\) is replaced by a wire of half length and half diameter that of \(\mathrm{R}\) of same material, then the balancing distance \(\left.l^{\prime} \text { (in } \mathrm{cm}\right)\) will now be
2020 Hard - 229. In the circuit, given in the figure currents in different branches and value of one resistor are shown. Then potential at point \(B\) with respect to the point \(A\) is\(.......V\)
2020 Hard - 230. In the figure shown, the current in the \(10\, V\) battery is close to
2020 Medium - 231. Model a torch battery of length \(l\) to be made up of a thin cylindrical bar of radius \('a'\) and a concentric thin cylindrical shell of radius ' \(b\) ' fille in between with an electrolyte of resistivity \(\rho\) (see figure). If the battery is connected to a resistance of value \(R ,\) the maximum Joule heating in \(R\) will take place for
2020 Hard - 232. The balancing length for a cell is \(560 \;\mathrm{cm}\) in a potentiometer experiment. When an external resistance of \(10 \;\Omega\) is connected in parallel to the cell, the balancing length changes by \(60\; \mathrm{cm} .\) If the internal resistance of the cell is \(\frac{\mathrm{N}}{10} \;\Omega,\) where \(\mathrm{N}\) is an integer then value of \(\mathrm{N}\) is 2020 Medium
- 233. The current \(I_{1}\) (in \(A\)) flowing through \(1\; \Omega\) resistor in the following circuit is:
2020 Medium - 234. The length of a potentiometer wire is \(1200\; \mathrm{cm}\) and it carries a current of \(60 \;\mathrm{mA}\). For a cell of \(emf\;5\; \mathrm{V}\) and intemal resistance of \(20\; \Omega,\) the null point on it is found to be a \(1000\; \mathrm{cm} .\) The resistance of whole wire is .............. \(\Omega\) 2020 Medium
- 235. The series combination of two batteries, both of the same emf \(10 \mathrm{\;V},\) but different internal resistance of \(20\; \Omega\) and \(5\; \Omega,\) is connected to the parallel combination of two resistors \(30\; \Omega\) and \(\mathrm{R}\; \Omega .\) The voltage difference across the battery of internal resistance \(20\; \Omega\) is zero, the value of \(\mathrm{R}(\text { in } \Omega)\) is 2020 Hard
- 236. The value of current \(i_{1}\) flowing from \(A\) to \(C\) in the circuit diagram is\(.......A\)
2020 Medium - 237. Two resistors \(400\, \Omega\) and \(800\, \Omega\) are connected in series across a \(6 V\) battery. The potential difference measured by a voltmeter of \(10\, k \Omega\) across \(400\, \Omega\) resistor is close to\(....V\) 2020 Medium
- 238. Which of the following will NOT be observed when a multimeter (operating in resistance measuring mode) probes connected across a component, are just reversed? 2020 Medium
- 239. A \(2\, W\) carbon resistor is color coded with green, black, red and brown respectively. The maximum current which can be passed through this resistor is .............. \(mA\) 2019 Medium
- 240. A \(200\,\Omega \) resistor has a certain color code. If one replaces the red color by green in the code, the new resistance will be .............. \(\Omega\) 2019 Medium
- 241. A carbon resistance has a following colour code. What is the value of the resistance?
2019 Medium - 242. A cell of internal resistance \(r\) drives current through an external resistance \(R\) . The power delivered by the cell to the external resistance will be maximum when: 2019 Medium
- 243. A copper wire is stretched to make it \(0.5\%\) longer. The percentage change in its electric resistance if its volume remains unchanged is ................ \(\%\) 2019 Medium
- 244. A current of \(2\, mA\) was passed through an unknown resistor which dissipated a power of \(4.4\, W\). Dissipated power when an ideal power supply of \(11\, V\) is connected across it is 2019 Medium
- 245. A current of \(5\, A\) passes through a copper conductor (resistivity \(= 1.7\times10^{-8}\,\Omega \,m\)) of radius of cross-section \(5\, mm\). Find the mobility of the charges if their drift velocity is \(1.1\times10^{-3}\, m/s\) ................ \(m^2/Vs\) 2019 Medium
- 246. A metal wire of resistance \(3\,\Omega \) is elongated to make a uniform wire of double its previous length. The new wire is now bent and the ends joined to make a circle. If two points on this circle make an angle \(60^o\) at the centre, the equivalent resistance between these two points will be 2019 Medium
- 247. A potentiometer wire \(AB\) having length \(L\) and resistance \(12\, r\) is joined to a cell \(D\) of \(emf\) \(\varepsilon \) and internal resistance \(r\). A cell \(C\) having \(emf\) \(\varepsilon /2\) and internal resistance \(3r\) is connected. The length \(AJ\) at which the galvanometer as shown in figure shows no deflection is
2019 Medium - 248. A resistance is shown in the figure. Its value and tolerance are given respectively by
2019 Medium - 249. A wire of resistance \(R\) is bent to form a square \(ABCD\) as shown in the figure. The effective resistance between \(E\) and \(C\) is ( \(E\) is mid-point of arm \(CD\) )
2019 Medium - 250. An ideal battery of \(4\, V\) and resistance \(R\) are connected in series in the primary circuit of a potentiometer of length \(1\, m\) and resistance \(5\,\Omega \) . The value of \(R\), to give a difference of \(5\, mV\) across \(10\, cm\) of potentiometer wire, is: ................ \(\Omega\) 2019 Medium
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