Current Electricity PYQs

The current (I) in the circuit shown below is: (All diodes are ideal and identical)

A resistor is connected to a battery of 12 V emf and internal resistance 2 Ω. If the current in the circuit is 0.6 A, the terminal voltage of the battery is:

A uniform metallic wire having resistance 4 Ω is bent to form a square loop (ABCD). A resistance of 2 Ω is connected between points B and D and a battery of 2 V is connected across points A and C as shown. The value of current I is:

A room heater is rated 400 W, 220 V. If the supply voltage drops to 200 V, what will be the power consumed (approximately)?

In a metre bridge experiment (see figure), the positions of the cell E and galvanometer G are interchanged. We shall observe in the galvanometer:

The current passing through the battery in the given circuit, is:

A wire of resistance R is cut into 8 equal pieces. From these pieces two equivalent resistances are made by adding four of these pieces together in parallel. Then these two sets are added in series. The effective resistance of the combination is :

A constant voltage of 50 V is maintained between the points A and B of the circuit shown in the figure. The current through the branch CD of the circuit is :

A wire of length 'l' and resistance 100 Ω is divided into 10 equal parts. The first 5 parts are connected in series while the next 5 parts are connected in parallel. The two combinations are again connected in series. The resistance of this final combination is:

The terminal voltage of the battery, whose emf is 10 V and internal resistance 1 Ω, when connected through an external resistance of 4 Ω as shown in the figure is:

Two heaters A and B have power rating of 1 kW and 2 kW, respectively. Those two are first connected in series and then in parallel to a fixed power source. The ratio of power outputs for these two cases is:

A parallel plate capacitor is charged by connecting it to a battery through a resistor. If I is the current in the circuit, then in the gap between the plates:

Choose the correct circuit which can achieve the bridge balance.

If the galvanometer G does not show any deflection in the circuit shown, the value of R is given by :

Resistance of a carbon resistor determined from colour codes is (22000 ± 5%) Ω. The colour of third band must be :

The magnitude and direction of the current in the following circuit is :

10 resistors, each of resistance R are connected in series to a battery of emf E and negligible internal resistance. Then those resistors are connected in parallel to the same battery, the current is increased n times. The value of n is:

The resistance of platinum wire at 0°C is 2Ω and 6.8Ω at 80°C. The temperature coefficient of resistance of the wire is:

Two resistors of resistance, 100 Ω and 200 Ω are connected in parallel in an electrical circuit. The ratio of the thermal energy developed in 100 Ω to that in 200 Ω in a given time is

As the temperature increases, the electrical resistance

A copper wire of length $10\,m$ and radius $\left(\frac{10^{-2}}{\sqrt{\pi}}\right)\,m$ has electrical resistance of $10\,\Omega$. The current density in the wire for an electric field strength of $10\,(V/m)$ is

A Wheatstone bridge is used to determine the value of unknown resistance X by adjusting the variable resistance Y as shown in the figure. For the most precise measurement of X, the resistances P and Q:

Column-I gives certain physical terms associated with flow of current through a metallic conductor. Column-II gives some mathematical relations involving electrical quantities. Match Column-I and Column-II with appropriate relations.Choose the correct option:

The effective resistance of a parallel connection that consists of four wires of equal length, equal area of cross-section and same material is 0.25 Ω. What will be the effective resistance if they are connected in series?

In a potentiometer circuit a cell of EMF 1.5 V gives balance point at 36 cm length of wire. If another cell of EMF 2.5 V replaces the first cell, then at what length of the wire will the balance point occur?

Three resistors having resistances r₁, r₂ and r₃ are connected as shown in the circuit. The ratio i₃/i₁ of currents in terms of resistances used in the circuit is

The energy required to break one bond in DNA is 10⁻²⁰ J. This value in eV is nearly:

Which of the following graph represents the variation of resistivity (ρ) with temperature (T) for copper?

The color code of a resistance is given below. The values of resistance and tolerance, respectively, are:

A charged particle having drift velocity of 7.5 × 10⁻⁴ m s⁻¹ in an electric field of 3 × 10⁻¹⁰ V m⁻¹, has a mobility in m² V⁻¹ s⁻¹ of :

A resistance wire connected in the left gap of a metre bridge balances a 10 Ω resistance in the right gap at a point which divides the bridge wire in the ratio 3 : 2. If the length of the resistance wire is 1.5 m, the length of 1 Ω of the resistance wire is:

The reading of an ideal voltmeter in the circuit shown is,

The metre bridge shown is in balance position with $\frac{P}{Q} = \frac{l_1}{l_2}$. If we now interchange the positions of galvanometer and cell, will the bridge work? If yes, what will be balance condition?

A carbon resistor of (47 ± 4.7) kΩ is to be marked with rings of different colours for its identification. The colour code sequence will be:

A set of 'n' equal resistors, of value 'R' each, are connected in series to a battery of emf 'E' and internal resistance 'R'. The current drawn is I. Now, the 'n' resistors are connected in parallel to the same battery. Then the current drawn from battery becomes 10 I. The value of 'n' is:

A battery consists of a variable number 'n' of identical cells (having internal resistance 'r' each) which are connected in series. The terminals of the battery are short-circuited and the current I is measured. Which of the graphs shows the correct relationship between I and n?

In a common emitter transistor amplifier the audio signal voltage across the collector is $3\ \text{V}$. The resistance of collector is $3\ \text{k}\Omega$. If current gain is $100$ and the base resistance is $2\ \text{k}\Omega$, the power gain of the amplifier is

Figure shows a circuit contains three identical resistors with resistance $R = 9.0\ \Omega$ each, two identical inductors with inductance $L = 2.0\ \text{mH}$ each, and an ideal battery with $\varepsilon = 18\ \text{V}$. The current $i$ through the battery just after the switch is closed is

The resistance of a wire is $R\,\Omega$. If it is melted and stretched to $n$ times its original length, then its new resistance will be:

A potentiometer is an accurate and versatile device to make electrical measurements of E.M.F. because the method involves:

The potential difference $(V_A - V_B)$ between the points $A$ and $B$ in the given figure is:

A filament lamp $(500\ \text{W},\ 100\ \text{V})$ is to be used in a $230\ \text{V}$ main supply. When a resistance $R$ is connected in series, it works perfectly and consumes $500\ \text{W}$. The value of $R$ is:

A potentiometer wire of length $L$ and resistance $r$ are connected in series with a battery of e.m.f. $E_0$ and a resistance $r_1$. An unknown e.m.f. $E$ is balanced at a length $\ell$ of the potentiometer wire. The e.m.f. $E$ will be:

Two metal wires of identical dimensions are connected in series. If $\sigma_1$ and $\sigma_2$ are the conductivities of the metal wires respectively, the effective conductivity of the combination is:

A circuit contains an ammeter, a battery of 30 V and a resistance 40.8 ohm all connected in series. If the ammeter has a coil of resistance 480 ohm and a shunt of 20 ohm, the reading in the ammeter will be :-

Two cities are $150\,\mathrm{km}$ apart. Electric power is sent from one city to another through copper wires. The fall of potential per kilometre is $8\,\mathrm{V}$ and the average resistance per kilometre is $0.5\,\Omega$. The power loss in the wires is:

The resistance in the two arms of the meter bridge are 5Ω and RΩ, respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6 ℓ₁. The resistance R is:

A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery used across the potentiometer wire has an emf of 2.0 V and negligible internal resistance. The potentiometer wire itself is 4m long. When the resistance R connected across the given cell has values of (i) infinity (ii) 9.5 Ω, the balancing lengths on the potentiometer wire are found to be 3 m and 2.85 m, respectively. The value of the internal resistance of the cell is:

The following four wires are made of the same material. Which of these will have the largest extension when the same tension is applied?

A wire of resistance $4\,\Omega$ is stretched to twice its original length. The resistance of stretched wire would be

The internal resistance of a $2.1\,V$ cell which gives current of $0.2\,A$ through a resistance of $10\,\Omega$ is

The resistances of the four arms P, Q, R and S in a Wheatstone's bridge are $10\,\Omega$, $30\,\Omega$, $30\,\Omega$ and $90\,\Omega$ respectively. The e.m.f. and internal resistance of the cell are $7\,V$ and $5\,\Omega$ respectively. If the galvanometer resistance is $50\,\Omega$, the current drawn from the cell will be

The power dissipated in the circuit shown in the figure is 30 watts. The value of resistance R is:

A cell having an emf ε and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by:

A galvanometer of resistance G is shunted by a resistance S ohm. To keep the main current in the circuit unchanged, the resistance to be put in series with the galvanometer is:

A thermocouple of negligible resistance produces an e.m.f. of 40 μV/°C in the linear range of temperature. A galvanometer of resistance 10 ohm whose sensitivity is 1 μA/division, is employed with the thermocouple. The smallest value of temperature difference that can be detected by the system will be:

In the circuit shown in the figure, if potential at point A is taken to be zero, the potential at point B is:

A wire of resistance $12\,\Omega$ per metre is bent to form a complete circle of radius $10\,cm$. The resistance between its two diametrically opposite points A and B is:

See the electrical circuit shown in the figure. Which one of the following equations is a correct equation for it?

A galvanometer having a coil resistance of $60\,\Omega$ shows full scale deflection when a current of $1.0\,A$ passes through it. It can be converted into an ammeter to read currents up to $5.0\,A$ by:

A student measures the terminal potential difference $(V)$ of a cell (emf $\varepsilon$ and internal resistance $r$) as a function of current $(I)$ flowing through it. The slope and intercept of the graph between $V$ and $I$ are respectively equal to:

The mean free path of electrons in a metal is $4 \times 10^{-8}\,\text{m}$. The electric field which can give on an average $2\,\text{eV}$ energy to an electron in the metal will be in units of $\text{V/m}$:

A cell can be balanced against 110 cm and 100 cm of potentiometer wire, respectively with and without being short-circuited through a resistance of 10 Ω. Its internal resistance is

A wire of a certain material is stretched slowly by ten per cent. Its new resistance and specific resistance become respectively

In the circuit shown, the current through the 4 Ω resistor is 1 A when the points P and M are connected to a d.c. voltage source. The potential difference between the points M and N is

A current of 3 amp. flows through the 2 Ω resistor shown in the circuit. The power dissipated in the 5 Ω resistor is

When 4 A current flows through a battery from positive to negative terminal, the terminal potential difference is 12 V. When 2 A current passes from negative to positive terminal of the battery, the terminal potential difference is 9 V. Calculate the emf and internal resistance of the battery.

In the circuit shown, if a conducting wire is connected between points A and B, the current in this wire will:

Two cells, having the same emf, are connected in series through an external resistance R. Cells have internal resistances r₁ and r₂ (r₁ > r₂) respectively. When the circuit is closed, the potential difference across the first cell is zero. The value of R is:

Power dissipated across the 8 Ω resistor in the circuit shown here is 2 W. The power dissipated across the 3 Ω resistor is:

Kirchhoff's first and second laws for electrical circuits are consequences of:

Two batteries, one of emf $18\,V$ and internal resistance $2\,\Omega$ and the other of emf $12\,V$ and internal resistance $1\,\Omega$, are connected as shown. The voltmeter $V$ will record a reading of:

For the network shown in the figure, the value of current $i$ is:

When a wire of uniform cross-section, length l and resistance R is bent into a complete circle, the resistance between two diametrically opposite points is:

A 5-A fuse wire can withstand a maximum power of 1 W in circuit. The resistance of the fuse wire is: