A potentiometer wire, $10\,m$ long, has a resistance of $40\,\Omega $. It is connected in series with a resistance box and a $2\,V$ storage cell. If the potential gradient along the wire is $0.1\,m\,V/cm$, the resistance unplugged in the box is .............. $\Omega$
Medium
Download our app for free and get started
Potential gradient along wire $=\frac{\text { potential difference along wire }}{\text { length of wire }}$
or, $0.1 \times 10^{-3}=\frac{1 \times 40}{1000} \,\mathrm{V} / \mathrm{cm}$
or, Current in wire, $I$ $=\frac{1}{400} \,\mathrm{A}$
or, $\frac{2}{40+R}=\frac{1}{400}$ or $R=800-40=760\,\Omega$
Download our appand 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.*
Similar Questions
- 1The figure shows a network of resistances in which the point $A$ is earthed. The current through the $4\,\Omega$ resistor isView Solution
- 2View SolutionA bird sitting on a single high tension wire does not get electrocuted because
- 3A potentiometer is an accurate and versatile device to make electrical measurements of $EMF$ because the method involvesView Solution
- 4$12$ cells each having the same emf are connected in series and are kept in a closed box. Some of the cells are wrongly connected. This battery is connected in series with an ammeter and two cells identical with each other and also identical with the previous cells. The current is $3\, A$ when the external cells aid this battery and is $2\,A$ when the cells oppose the battery. How many cells in the battery are wrongly connected :-View Solution
- 5View SolutionA wire is broken in four equal parts. A packet is formed by keeping the four wires together. The resistance of the packet in comparison to the resistance of the wire will be
- 6The resistance of a wire is $5\,ohm$ at $50\,^o C$ and $6\,ohm $ at $100\,^o C$. The resistance of the wire at $0\,^o C$ will be .............. $\Omega$View Solution
- 7A battery of $e.m.f.$ $10\, V$ and internal resistance $0.5\, ohm$ is connected across a variable resistance $R$. The value of $R$ for which the power delivered in it is maximum is given by ......... $ohm$View Solution
- 8The equivalent resistance between $x$ and $y$ in the circuit shown is ............. $\Omega$View Solution
- 9When a wire of uniform cross-section $a$, length $l$ and resistance $R$ is bent into a complete circle, resistance between any two of diametrically opposite points will beView Solution
- 10Two $220\; V , 100 \;W$ bulbs are connected first in series and then in parallel. Each time the combination is connected to a $220 \;V \;AC$ supply line. The power drawn by the combination in each case respectively will beView Solution