List of practice Questions

An ammeter, voltmeter and a resistor are connected in series to a cell and the readings are noted as $I$ and $V$ . If another resistor $R$ is connected in parallel with voltmeter, then

In a closed circuit, the current $ I $ (in ampere) at an instant of time $t$ (in second) is given by $ I=4-0.08t $ . The number of electrons flowing in $ 50\, s $ through the cross-section of the conductor is

In a potentiometer experiment, when three cells $A, B$ and $C$ are connected in series the balancing length is found to be $740\, cm$. If $A$ and $B$ are connected in series balancing length is $440\, cm$ and for $B$ and $C$ connected in series that is $540 \,cm$. Then the emf of $ {{E}_{A}},{{E}_{B}} $ and $ {{E}_{C}} $ are respectively (in volts)

In a potentiometer of wire length $l$, a cell of emf $V$ is balanced at a length $\frac{l}{3}$ from the positive end of the wire. For another cell of emf $1.5\,V$, the balancing length becomes

In the figure shown below, the terminal voltage across $ {{E}_{2}} $ is

Nichrome is used as electrical heating element because of its

When two resistances $ {{R}_{1}} $ and $ {{R}_{2}} $ are connected in series, they consume $ 12 \,W $ power. When they are connected in parallel, they consume $ 50\, W $ power. What the ratio of the powers of $ {{R}_{1}} $ and $ {{R}_{2}} $ ?

$1$ ampere current is equivalent to

$8$ identical cells, each of emf $E$ and internal resistance $r$, are connected in series. If polarity of two cells is reversed then the total internal resistance in the circuit will be

A 10 m long wire of resistance $ 20O $ is connected in series with a battery ofemf3V and a resistance of $ 10O $ The potential gradient along the wire in V /m is

At room temperature, copper has free electron density of $8.4 \, \times \, 10^{28} \, m^{- 3}$ . The electron drift velocity in a copper conductor of cross-sectional area $10^{- 6} \, m^{2}$ and carrying a current of $5.4 \, A$ , will be -

A $220\, volts$ and $100\, watt$ bulb is connected to a $110$ volt source. What is the power consumed by the bulb?

A battery, an open switch and a resistor are connected in series as shown in figure.

Consider the following three statements concerning the circuit. A voltmeter will read zero if it is connected across points (i) $P$ and $T$ (ii) $P$ and $Q$ (iii) $Q$ and $T$ Which one of the above is/are true ?

A battery has e.m.f. $4V$ and internal resistance $r$. When this battery is connected to an external resistance of $2\,\Omega $, a current of $1A$ flows in the circuit. How much current will flow if the terminals of the battery are connected directly

A battery of emf $15\, V$ and internal resistance of $4\,\Omega$ is connected to a resistor. If the current in the circuit is $2 \,A$ and the circuit is closed. Resistance of the resistor and terminal voltage of the battery will be

A car battery of e.m.f. $12 V$ and internal resistance $5 \times 10^{-2} \Omega$ receives a current of $60 A$ from an external source, then terminal potential difference of battery is :-

A current in a wire is given by the equation, $I = 2t^2 - 3t + 1$, the charge through cross section of wire in time interval $t = 3\, s$ to $t = 5\,s$ is

A heater coil is cut into two equal parts and only one part is used in the heater, the heat generated becomes

A piece of wire of resistance 4 ohm is bent through 180 at its mid point and the two halves are twisted together. Then the resistance is

A potentiometer wire of length $100 \,cm$ has a resistance of $10 \,\Omega$. It is connected in series with a resistance and a cell of emf $2 \,V$ and of negligible internal resistance. A source of emf $10 \,mV$ is balanced against a length of $40 \,cm$ of the potentiometer wire. What is the value of external resistance ?

A voltmeter of resistance $R$ is to be used to measure the potential difference across a resistance $r$. The nearest reading in the absence of voltmeter ?

According to the Kirchhoffs law the sum of the products of current and resistance as well as emfs in a closed loop is :

All of the following statements are true except

An electric bulb rated 220V, 100W is connected to a source of 220 (0.8)V then actual power will be

An electric heater is connected to the voltage supply. After few seconds, current gets its steady value then its initial current will be