In the circuit shown, a four wire potentiometer is made of a $400\, cm$ long wire, which extends between $A$ and $B$. The resistance per unit length of the potentiometer wire is $r = 0.01\, \Omega /cm$. If an ideal voltmeter is connected as shown with jockey $J$ at $50\, cm$ from end $A$, the expected reading of the voltmeter will be: ............... $V$
A$0.75$
B$0.20$
C$0.25$
D$0.50$
JEE MAIN 2019, Medium
Download our app for free and get started
C$0.25$
c Resistance of wire $A B=400 \times 0.01=4 \,\Omega$ $\mathrm{i}=\frac{3}{6}=0.5\, \mathrm{A}$
Now voltmeter reading $=$ $i$ (Resistance of $50 \,\mathrm{cm}$ length)
$=(0.5 \mathrm{A})(0.01 \times 50)=0.25$ $volt$
Download our app
and get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Two wires each of radius of cross section $r$ but of different materials are connected together end to end (in series). If the densities of charge carriers in the two wires are in the ratio $1 : 4$, the drift velocity of electrons in 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 Wheatstone's bridge $P = 9\, ohm$, $Q = 11\, ohm$, $R = 4\,ohm$ and $S = 6\,ohm$. How much resistance must be put in parallel to the resistance $S$ to balance the bridge ............... $ohm$
The four arms of a Wheatstone bridge have resistances as shown in the figure. A galvanometer of $15\, \Omega$ resistance is connected across $BD$. Calculate the current through the galvanometer when a potential difference of $10\, V$ is maintained across $AC.$