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 by :

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 :

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

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 balance length is found to be at $$60\mathrm{cm}$$ from the left end. If the resistivity of the wire is $$\mathrm{R}\times 10^{-7}\Omega \mathrm{m}$$, then value of $$\mathrm{R}$$ 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 :

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.

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 :

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 ; $$S_1=X\left(\frac{\pi r^2}{L}\right)$$. If the length of the wire gets doubled then the value of specific resistance will be :

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

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 another wire of $$2r$$ resistance per centimeter. The new balancing length for same settings will be at

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 :

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 :

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 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 :

In the given circuit, the current in resistance R$${}_3$$ is :

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 dissipation rate will become:

A potential divider circuit is shown in figure. The output voltage V$${}_0$$ is :

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 temperature attained by toaster is around : ( if $$\alpha =2\times 10^{-4}$$/$${}^{\circ }\mathrm{C}$$)

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