In a building there are $15$ bulbs of $45\; \mathrm{W}, 15$ bulbs of $100\; \mathrm{W}, 15$ small fans of $10 \;\mathrm{W}$ and $2$ heaters of $1 \;\mathrm{kW}$. The voltage of electric main is $220\; \mathrm{V}$. The minimum fuse capacity (rated value) of the building will be: .......... $A$
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A potentiometer wire $AB$ having length $L$ and resistance $12\, r$ is joined to a cell $D$ of $emf$ $\varepsilon $ and internal resistance $r$. A cell $C$ having $emf$ $\varepsilon /2$ and internal resistance $3r$ is connected. The length $AJ$ at which the galvanometer as shown in figure shows no deflection is
When two resistance $R_1$ and $R_2$ connected in series and introduced into the left gap of a meter bridge and a resistance of $10 \Omega$ is introduced into the right gap, a null point is found at $60 cm$ from left side. When $R_1$ and $R_2$ are connected in parallel and introduced into the left gap, a resistance of $3 \Omega$ is introduced into the right-gap to get null point at 40 cm from left end. The product of $R_1 R_2$ is $.............\Omega$
A potentiometer consists of two wires $AC$ and $CB$ of same material and of equal lengths but diameters in the ratio $3 : 1.$ Then the potential gradients on the two wires will be in the ratio :-
In an electrical cable there is a single wire of radius $9\, mm$ of copper. Its resistance is $5\,\Omega $. The cable is replaced by $6$ different insulated copper wires, the radius of each wire is $3\,mm$. Now the total resistance of the cable will be ............... $\Omega$
In the meter bridge shown, the resistance $X$ has a negative temperature coefficient of resistance. Neglecting the variation in other resistors, when current is passed for some time, in the cirucit, balance point should shift towards.
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 :