Current Electricity PYQs Set 13 (PDF)

Set 13 of 25 · Questions 361-390 of 723

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Mere Teacher · Previous Year Questions JEE Main Physics · Current Electricity · Set 13 (Q361-390)
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361. $The I - V graphs for two different electrical appliances P and Q are shown in the diagram. If R_{p} and R_{Q} be the resistances of the devices, then$ (1) $R_{p} = R_{0}$ (2) $R_{p} > R_{Q}$ (3) $R_{p} < R_{Q}$ (4) $R_{p} = \frac{R _{Q}}{2}$ 362. $A battery of emf E has an internal resistance ' r '. A variable resistance R is connected to the terminals of the battery. A current I is drawn from the battery. V is the terminal P.D. If R alone is gradually reduced to zero, which of the following best describes I and V?$ (1) $I approaches zero, V approaches E$ (2) $I approaches E / r, V approaches zero$ (3) $I approaches E / r, V approaches E$ (4) $I approaches infinity, V approaches E$ 363. $The total length of potentiometer wire AB is 50 cm in the arrangement as shown in figure. If P is the point where the galvanometer shows zero reading then the length AP is____cm.$ (1) $25$ (2) $30$ (3) $20$ (4) $15$ 364. $Statement-I: In a Meter Bridge experiment, null point for an unknown resistance is measured. Now, the unknown resistance is put inside an enclosure maintained at a higher temperature. The null point can be obtained at the same point as before by decreasing the value of the standard resistance. Statement-II: Resistance of a metal increases with increase in temperature.$ (1) $Statement -I is True, Statement -II is True; Statement -II is a correct explanation for Statement -I$ (2) $Statement -I is True, Statement -II is True; Statement -II is NOT a correct explanation for Statement -I$ (3) $Statement -I is True, Statement -II is False$ (4) $Statement -I is False, Statement-II is True.$ 365. $The Wheatstone bridge shown in Fig. here, gets balanced when the carbon resistor used as R_{1} has the colour code (Orange, Red, Brown). The resistors R_{2} and R_{4} are 80Ω and 40Ω, respectively. Assuming that the colour code for the carbon resistorsgives their accurate values, the colour code for the carbon resistor, used as R_{3}, would be:$ (1) $Brown, Blue, Brown$ (2) $Brown, Blue, Black$ (3) $Red, Green, Brown$ (4) $Grey, Black, Brown$ 366. $Two cells of internal resistances r_{1} and r_{2} and of same emf are connected in series across a resistor of resistance R . If the terminal potential difference across the cell of internal resistance r_{1} is zero, then the value of R is$ (1) $R = 2 (r_{1} + r_{2})$ (2) $R = r_{2} - r_{1}$ (3) $R = r_{1} - r_{2}$ (4) $R = 2 (r_{1} - r_{2})$ 367. $The resistive network shown below is connected to a D . C . source of 16 V . The power consumed by the network is 4 Watt. The value of R is$ (1) $6Ω$ (2) $8Ω$ (3) $1Ω$ (4) $16Ω$ 368. $When a metal conductor connected to left gap of a meter bridge is heated, the balancing point$ (1) $remains unchanged$ (2) $shifts towards right$ (3) $shifts to the center$ (4) $shifts towards left$ 369. $Consider the following statements regarding the network shown in the figure. (I) The equivalent resistance of the network between points A and B is independent of value of G. (II) The equivalent resistance of the network between points A and B is \frac{4}{3} R . (III) The current through G is zero. Which of the above statements is/are true?$ (1) $(I) alone$ (2) $(II) alone$ (3) $(II) and (III)$ (4) $(I), (II) and (III)$ 370. $The galvanometer deflection, when key K_{1} is closed but K_{2} is open, equals θ_{0} (see figure). On closing K_{2} also and adjusting R_{2} to 5Ω, the deflection in galvanometer becomes \frac{θ _{0}}{5} . The resistance of the galvanometer is, then, given by [Neglect the internal resistance of battery]:$ (1) $5Ω$ (2) $22Ω$ (3) $25Ω$ (4) $12Ω$ 371. $In the given circuit the cells have zero internal resistance. The currents (in Amperes) passing through resistance R_{1} and R_{2} respectively are:$ (1) $2, 2$ (2) $0, 0$ (3) $1, 2$ (4) $0.5, 0$ 372. $B_{1}, B_{2} and B_{3} are the three identical bulbs connected to a battery of steady e.m.f. with key K closed. What happens to the brightness of the bulbs B_{1} and B_{2} when the key is opened?$ (1) $Brightness of the bulbs B_{1} increases and that of B_{2} decreases.$ (2) $Brightness of the bulbs B_{1} and B_{2} increases.$ (3) $Brightness of the bulb, B_{1} decreases and that of B_{2} increases.$ (4) $Brightness of the bulbs B_{1} and B_{2} decreases$ 373. $In the given arrangement of experiment on meter bridge, if AD corresponding to null deflection of the galvanometer is x, what would be its yalue if the radius of the wire AB is doubled?$ (1) $x$ (2) $\frac{x}{4}$ (3) $4 x$ (4) $2 x$ 374. $Which of the following graph represents the variation of resistivity (ρ) with temperature (T) for copper? [NEET 2020]$ (1) (2) (3) (4) 375. $In the given circuit diagram, a wire is joining points B and D. The current in this wire is:$ (1) $zero$ (2) $2 A$ (3) $0.4 A$ (4) $4A$ 376. $A cell of emf 90 V is connected across series combination of two resistors each of 100 Ω resistance. A voltmeter of resistance 400 Ω is used to measure the potential difference across each resistor. The reading of the voltmeter will be:$ (1) $40 V$ (2) $45 V$ (3) $80 V$ (4) $90 V$ 377. $Three resistances P, Q, R each of 2 Ω and an unknown resistance S form the four arms of a Wheatstone bridge circuit. When a resistance of 6 Ω is connected in parallel to S the bridge gets balanced. What is the value of S .$ (1) $3 Ω$ (2) $6 Ω$ (3) $1 Ω$ (4) $2 Ω .$ 378. $The given potentiometer has its wire of resistance 10Ω . When the sliding contact is in the middle of the potentiometer wire, the potential drop across 2Ω resistor is:$ (1) $10V$ (2) $5V$ (3) $\frac{40}{9} V$ (4) $\frac{40}{11} V$ 379. $Two cells, having the same e.m.f. are connected in series through an external resistance R . Cells have internal resistances r_{1} and r_{2} (r_{1} > r_{2}) respectively. When the circuit is closed, the potential difference across the first cell is zero. The value of R is$ (1) $r_{1} + r_{2}$ (2) $r_{1} - r_{2}$ (3) $\frac{r _{1} + r _{2}}{2}$ (4) $\frac{r _{1} - r _{2}}{2}$ 380. $Two known resistances of RΩ and 2 RΩ and one unknown resistance XΩ are connected in a circuit as shown in the figure. If the equivalent resistance between points A and B in the circuit is XΩ, then the value of X is____Ω .$ (1) $(3 - 1) R$ (2) $2 (3 - 1) R$ (3) $(3 + 1) R$ (4) $R$ 381. $The value of current i_{1} flowing from A to C in the circuit diagram is$ (1) $5 A$ (2) $2 A$ (3) $4 A$ (4) $1 A$ 382. $In a Wheatstone’s bridge all the four arms have equal resistance R . If the resistance of the galvanometer arm is also R, the equivalent resistance of the combination as seen by the battery is$ (1) $R /4$ (2) $R /2$ (3) $R$ (4) $2 R$ 383. $The charge on a capacitor plate in a circuit, as a function of time, is shown in the figure: What is the value of current at t = 4 s ?$ (1) $Zero$ (2) $3 μA$ (3) $2 μA$ (4) $1.5 μA$ 384. $The effective resistance between P and Q for the following network is$ (1) $\frac{1}{12} Ω$ (2) $21Ω$ (3) $12Ω$ (4) $\frac{1}{21} Ω$ 385. $Ten identical cells connected in series are needed to heat a wire of length one meter and radius ‘ r ’ by 1 0^{o} C in time ‘ t ’. How many cells will be required to heat the wire of length two meter of the same radius by the same temperature in time ‘t’?$ (1) $20$ (2) $30$ (3) $40$ (4) $10$ 386. $Two batteries of emf 4 V and 8 V with internal resistance 1 Ω and 2 Ω are connected in a circuit with resistance of 9 Ω as shown in figure. The current and potential difference between the points P and Q are$ (1) $\frac{1}{3} A and 3 V$ (2) $\frac{1}{6} A and 4 V$ (3) $\frac{1}{9} A and 9 V$ (4) $\frac{1}{12} A and 12 V$ 387. $In the given figure an ammeter A consists of a 240Ω coil connected in parallel to a 10Ω shunt. The reading of the ammeter is mA$ 388. $A 220 V, 50 Hz AC source is connected to a 25 V, 5 W lamp and an additional resistance R in series (as shown in figure) to run the lamp at its peak brightness, then the value of R (in ohm) will _______ .$ 389. $Resistance are connected in a meter bridge circuit as shown in the figure. The balancing length l_{1} is 40cm. Now an unknown resistance x is connected in series with P and new balancing length is found to be 80cm measured from the same end. Then the value of x will be_____Ω$ 390. $In the following circuit, the current through the resistor R (= 2Ω) is I Amperes. The value of I is:$