The potential difference (V_A - V_B) between points A and B in the figure (current 2 A from A to B through 2 $\Omega$, a 3 V cell, then 1 $\Omega$) is:
The charge through a resistance R varies with time as Q = at - bt$^{2}$ (a, b positive constants). The total heat produced in R is:
A filament bulb (500 W, 100 V) is to be used in a 230 V supply. A resistance R is connected in series so it works perfectly at 500 W. The value of R is:
A potentiometer wire is 100 cm long with a constant PD across it. Two cells in series give balance at 50 cm (aiding) and 10 cm (opposing). The ratio of emfs is:
The resistance of a wire is R. If it is melted and stretched to n times its original length, its new resistance is:
A potentiometer is an accurate and versatile device to measure emf because the method involves:
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A carbon resistor of (47 ± 4.7) k$\Omega$ is to be marked with rings of different colours for its identification. The colour code sequence will be:
A set of 'n' equal resistors (R each) in series with a battery (emf E, internal resistance R) draws current I. In parallel they draw 10I. The value of n is:
A battery of n identical cells (each internal resistance r) in series is short-circuited and the current I measured. Which graph shows I vs n?
Six similar bulbs are connected as shown with a DC source of emf E and zero internal resistance. The ratio of power consumed when (i) all glow to (ii) when two of section A and one of section B glow, is:
The reading of an ideal voltmeter in the circuit shown is:
In the two circuits shown (same 10 V cell, same 10 $\Omega$ resistor; ideal meters, only the order of V and A swapped), the readings of the voltmeters and ammeters will be:
Which of the following acts as a circuit protecting device?
A metre bridge is balanced with P/Q = l$_{1}$/l$_{2}$. If the positions of galvanometer and cell are interchanged, will it balance, and what is the condition?
A charged particle having drift velocity 7.5$\times$10$^{-4}$ m s$^{-1}$ in an electric field of 3$\times$10$^{-10}$ V m$^{-1}$ has a mobility (in m$^{2}$ V$^{-1}$ s$^{-1}$) of:
A resistance wire in the left gap of a metre bridge balances a 10 $\Omega$ resistance in the right gap at a point dividing the wire 3:2. If the wire length is 1.5 m, the length corresponding to 1 $\Omega$ is:
The colour code of a resistance is given (Yellow, Violet, Brown, Gold). The values of resistance and tolerance, respectively, are:
The solids which have the negative temperature coefficient of resistance are:
Which of the following graphs represents the variation of resistivity ($\rho$) with temperature (T) for copper?
The effective resistance of four identical wires in parallel is 0.25 $\Omega$. Their effective resistance in series is:
In a potentiometer, a cell of emf 1.5 V balances at 36 cm. If a 2.5 V cell replaces it, the balance length is:
Three resistors r$_{1}$, r$_{2}$, r$_{3}$ are connected as shown. The ratio i$_{3}$/i$_{1}$ of currents in terms of the resistances is:
The electron concentration in an n-type semiconductor equals the hole concentration in a p-type. An electric field is applied across each. Compare the currents:
Match Column-I with Column-II: Column-I (A) Drift velocity (B) Electrical resistivity (C) Relaxation period (D) Current density Column-II (P) $m/(ne^{2}\rho)$ (Q) $ne\cdot v_d$ (R) $(eE/m)\tau$ (S) $E/J$ Choose the correct match:
A copper wire of length 10 m and radius (10$^{-2}$/$\surd\pi$) m has resistance 10 $\Omega$. The current density for an electric field strength of 10 V/m is:
Two resistors 100 $\Omega$ and 200 $\Omega$ are connected in parallel. The ratio of thermal energy developed in 100 $\Omega$ to that in 200 $\Omega$ in a given time is:
As the temperature increases, the electrical resistance:
A Wheatstone bridge is used to determine an unknown resistance X by adjusting the variable resistance Y. For the most precise measurement of X, the resistances P and Q:
10 resistors (R each) in series with a battery (emf E, negligible internal resistance); then connected in parallel — the current increases n times. The value of n is:
The magnitude and direction of the current in the following circuit is:
A copper wire of radius 1 mm contains 10$^{22}$ free electrons per m$^{3}$. The drift velocity for a 10 A current is (e = 1.6$\times$10$^{-19}$ C):
If the galvanometer G does not show any deflection in the circuit shown, the value of R is given by:
Wire A has resistance 81 $\Omega$. Wire B (same material, equal length, diameter three times that of A) has resistance:
On the basis of electrical conductivity, which one of the following materials has the smallest resistivity?
The emf of a cell (internal resistance 1 $\Omega$) balances at 330 cm on a potentiometer. With a 2 $\Omega$ external resistance across the cell, the balance length is:
Resistance of a carbon resistor from colour codes is (22000 ± 5%) $\Omega$. The colour of the third band must be:
The resistance of a platinum wire is 2 $\Omega$ at 0$^\circ$C and 6.8 $\Omega$ at 80$^\circ$C. The temperature coefficient of resistance is:
Choose the correct circuit which can achieve the bridge balance. (Arms 100 $\Omega$, 10 $\Omega$, 15 $\Omega$, 5 $\Omega$ with galvanometer G and cell E + key K.)
A wire of resistance 100 $\Omega$ is divided into 10 equal parts. The first 5 are connected in series, the next 5 in parallel; the two combinations are then in series. The resistance of the final combination is:
The terminal voltage of a battery of emf 10 V and internal resistance 1 $\Omega$, connected to an external resistance of 4 $\Omega$, is:
Two heaters A and B rated 1 kW and 2 kW are connected first in series and then in parallel to a fixed source. The ratio of power outputs (series : parallel) is:
A wire of resistance R is cut into 8 equal pieces. Two sets are made by joining four pieces in parallel each; the two sets are then in series. The net resistance is:
A constant voltage of 50 V is maintained between points A and B of the circuit shown. The current through the branch CD of the circuit is:
The current passing through the battery in the given circuit is:
A resistor is connected to a battery of emf 12 V and internal resistance 2 $\Omega$. If the current is 0.6 A, the terminal voltage of the battery is:
Consider two circuits A and B, each with two resistors. One resistor has a positive temperature coefficient $+\alpha$ and the other $-\alpha$. In circuit A the two are in series; in circuit B they are in parallel, across the same battery. At the initial temperature each resistance is $R_0$. As temperature increases, the correct statement about the currents $I_A$ and $I_B$ is:
In a metre bridge experiment, the positions of the cell E and galvanometer G are interchanged. In the galvanometer we shall observe:
A room heater is rated 400 W, 220 V. If the supply voltage drops to 200 V, the power consumed (approximately) is:
A uniform metallic wire of resistance 4 $\Omega$ is bent to form a square loop ABCD. A resistance of 2 $\Omega$ is connected between B and D, and a battery of 2 V across A and C. The value of current i is:
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