Current Electricity

The effective resistance between \(A\) and \(B\), if resistance of each resistor is \(R\), will be :

To determine the resistance (R) of a wire, a circuit is designed below. The \(V\)-\(I\) characteristic curve for this circuit is plotted for the voltmeter and the ammeter readings as shown in figure. The value of $R$ is _________ \(\Omega\)...

At room temperature \((27^{\circ} \mathrm{C})\), the resistance of a heating element is \(50 \Omega\). The temperature coefficient of the material is \(2.4 \times 10^{-4}{ }^{\circ} \mathrm{C}^{-1}\). The temperature of the element, when it...

In the given circuit, the terminal potential difference of the cell is :

Resistance of a wire at \(0^{\circ} \mathrm{C}, 100^{\circ} \mathrm{C}\) and \(t^{\circ} \mathrm{C}\) is found to be \(10 \Omega, 10.2 \Omega\) and \(10.95 \Omega\) respectively. The temperature \(t\) in Kelvin scale is _________.

A heater is designed to operate with a power of \(1000 \mathrm{~W}\) in a \(100 \mathrm{~V}\) line. It is connected in combination with a resistance of \(10 \Omega\) and a resistance \(R\), to a \(100 \mathrm{~V}\) mains as shown in figure....

Water boils in an electric kettle in 20 minutes after being switched on. Using the same main supply, the length of the heating element should be _________ to __________ times of its initial length if the water is to be boiled in 15 minutes.

The value of unknown resistance \((x)\) for which the potential difference between \(B\) and \(D\) will be zero in the arrangement shown, is :

A wire of resistance \(R\) and radius \(r\) is stretched till its radius became \(r / 2\). If new resistance of the stretched wire is \(x ~R\), then value of \(x\) is ________.

In the given figure an ammeter A consists of a \(240 \Omega\) coil connected in parallel to a \(10 \Omega\) shunt. The reading of the ammeter is ________ \(\mathrm{mA}\).

The number of electrons flowing per second in the filament of a \(110 \mathrm{~W}\) bulb operating at \(220 \mathrm{~V}\) is : (Given \(\mathrm{e}=1.6 \times 10^{-19} \mathrm{C}\))

In the given figure \(\mathrm{R}_1=10 \Omega, \mathrm{R}_2=8 \Omega, \mathrm{R}_3=4 \Omega\) and \(\mathrm{R}_4=8 \Omega\). Battery is ideal with emf \(12 \mathrm{~V}\). Equivalent resistant of the circuit and current supplied by battery ar...

In the experiment to determine the galvanometer resistance by half-deflection method, the plot of \(1 / \theta\) vs the resistance (R) of the resistance box is shown in the figure. The figure of merit of the galvanometer is _________ $$\tim...

The ratio of heat dissipated per second through the resistance \(5 \Omega\) and \(10 \Omega\) in the circuit given below is:

A wire of resistance \(20 \Omega\) is divided into 10 equal parts, resulting pairs. A combination of two parts are connected in parallel and so on. Now resulting pairs of parallel combination are connected in series. The equivalent resistan...

A galvanometer of resistance \(100 \Omega\) when connected in series with \(400 \Omega\) measures a voltage of upto \(10 \mathrm{~V}\). The value of resistance required to convert the galvanometer into ammeter to read upto $$10 \mathrm{~A}$...

Twelve wires each having resistance \(2 \Omega\) are joined to form a cube. A battery of \(6 \mathrm{~V}\) emf is joined across point \(a\) and \(c\). The voltage difference between \(e\) and \(f\) is ________ V.

To measure the internal resistance of a battery, potentiometer is used. For \(R=10 \Omega\), the balance point is observed at \(l=500 \mathrm{~cm}\) and for \(\mathrm{R}=1 \Omega\) the balance point is observed at \(l=400 \mathrm{~cm}\). Th...

An electric bulb rated \(50 \mathrm{~W}-200 \mathrm{~V}\) is connected across a \(100 \mathrm{~V}\) supply. The power dissipation of the bulb is:

Two wires \(A\) and \(B\) are made up of the same material and have the same mass. Wire \(A\) has radius of \(2.0 \mathrm{~mm}\) and wire \(B\) has radius of \(4.0 \mathrm{~mm}\). The resistance of wire \(B\) is \(2 \Omega\). The resistance...

Equivalent resistance of the following network is __________ \(\Omega\).

Two conductors have the same resistances at \(0^{\circ} \mathrm{C}\) but their temperature coefficients of resistance are \(\alpha_1\) and \(\alpha_2\). The respective temperature coefficients for their series and parallel combinations are ...

In the following circuit, the battery has an emf of \(2 \mathrm{~V}\) and an internal resistance of \(\frac{2}{3} \Omega\). The power consumption in the entire circuit is _________ W.

The resistance per centimeter of a meter bridge wire is \(r\), with \(X \Omega\) resistance in left gap. Balancing length from left end is at \(40 \mathrm{~cm}\) with \(25 \Omega\) resistance in right gap. Now the wire is replaced by anothe...

By what percentage will the illumination of the lamp decrease if the current drops by 20%?

Two cells are connected in opposition as shown. Cell \(\mathrm{E}_1\) is of \(8 \mathrm{~V}\) emf and \(2 \Omega\) internal resistance; the cell \(\mathrm{E}_2\) is of \(2 \mathrm{~V}\) emf and \(4 \Omega\) internal resistance. The terminal...

An electric toaster has resistance of \(60 \Omega\) at room temperature \(\left(27^{\circ} \mathrm{C}\right)\). The toaster is connected to a \(220 \mathrm{~V}\) supply. If the current flowing through it reaches \(2.75 \mathrm{~A}\), the te...

A potential divider circuit is shown in figure. The output voltage V\(_0\) is :

Two resistance of \(100 \Omega\) and \(200 \Omega\) are connected in series with a battery of \(4 \mathrm{~V}\) and negligible internal resistance. A voltmeter is used to measure voltage across \(100 \Omega\) resistance, which gives reading...

When a potential difference \(V\) is applied across a wire of resistance \(R\), it dissipates energy at a rate \(W\). If the wire is cut into two halves and these halves are connected mutually parallel across the same supply, the energy dis...

The electric current through a wire varies with time as \(I=I_0+\beta t\), where \(I_0=20 \mathrm{~A}\) and \(\beta=3 \mathrm{~A} / \mathrm{s}\). The amount of electric charge crossed through a section of the wire in \(20 \mathrm{~s}\) is :

A galvanometer having coil resistance \(10 \Omega\) shows a full scale deflection for a current of \(3 \mathrm{~mA}\). For it to measure a current of \(8 \mathrm{~A}\), the value of the shunt should be:

The deflection in moving coil galvanometer falls from 25 divisions to 5 division when a shunt of \(24 \Omega\) is applied. The resistance of galvanometer coil will be :

In the given circuit, the current flowing through the resistance \(20 \Omega\) is \(0.3 \mathrm{~A}\), while the ammeter reads \(0.9 \mathrm{~A}\). The value of \(\mathrm{R}_1\) is _________ \(\Omega\).

In the given circuit, the current in resistance R\(_3\) is :

A wire of resistance \(\mathrm{R}\) and length \(\mathrm{L}\) is cut into 5 equal parts. If these parts are joined parallely, then resultant resistance will be :

A wire of length \(10 \mathrm{~cm}\) and radius \(\sqrt{7} \times 10^{-4} \mathrm{~m}\) connected across the right gap of a meter bridge. When a resistance of \(4.5 \Omega\) is connected on the left gap by using a resistance box, the balanc...

Wheatstone bridge principle is used to measure the specific resistance \(\left(S_1\right)\) of given wire, having length \(L\), radius \(r\). If \(X\) is the resistance of wire, then specific resistance is ; $$S_1=X\left(\frac{\pi r^2}{L}\r...

A current of \(200 \mu \mathrm{A}\) deflects the coil of a moving coil galvanometer through \(60^{\circ}\). The current to cause deflection through \(\frac{\pi}{10}\) radian is :

Three voltmeters, all having different internal resistances are joined as shown in figure. When some potential difference is applied across \(A\) and \(B\), their readings are \(V_1, V_2\) and \(V_3\). Choose the correct option.

The current in a conductor is expressed as $I=3 t^2+4 t^3$, where $I$ is in Ampere and $t$ is in second. The amount of electric charge that flows through a section of the conductor during $t=1 \mathrm{~s}$ to $t=2 \mathrm{~s}$ is __________...

A galvanometer has a resistance of $50 ~\Omega$ and it allows maximum current of $5 \mathrm{~mA}$. It can be converted into voltmeter to measure upto $100 \mathrm{~V}$ by connecting in series a resistor of resistance :

The reading in the ideal voltmeter $(\mathrm{V})$ shown in the given circuit diagram is :

In an ammeter, $5 \%$ of the main current passes through the galvanometer. If resistance of the galvanometer is $\mathrm{G}$, the resistance of ammeter will be :

In a metre-bridge when a resistance in the left gap is $2 \Omega$ and unknown resistance in the right gap, the balance length is found to be $40 \mathrm{~cm}$. On shunting the unknown resistance with $2 \Omega$, the balance length changes b...

A current of \(2 \mathrm{~A}\) flows through a wire of cross-sectional area \(25.0 \mathrm{~mm}^{2}\). The number of free electrons in a cubic meter are \(2.0 \times 10^{28}\). The drift velocity of the electrons is __________ $$\times 10^{...

The number density of free electrons in copper is nearly \(8 \times 10^{28} \mathrm{~m}^{-3}\). A copper wire has its area of cross section \(=2 \times 10^{-6} \mathrm{~m}^{2}\) and is carrying a current of \(3.2 \mathrm{~A}\). The drift sp...

The equivalent resistance between A and B as shown in figure is:

The length of a metallic wire is increased by \(20 \%\) and its area of cross section is reduced by \(4 \%\). The percentage change in resistance of the metallic wire is __________.

As shown in the figure, the voltmeter reads \(2 \mathrm{~V}\) across \(5 ~\Omega\) resistor. The resistance of the voltmeter is _________ \(\Omega\).