Umakant Kondapure, Collin Fernandes, Nipun Bhatia, Vikram Bathula and, Ketki Deshpande Solutions for Chapter: Current Electricity, Exercise 1: Classical Thinking

The potential gradient along the length of a uniform wire is $10 \mathrm{V} {\mathrm{m}}^{-1}$. The length of the wire is $1 \mathrm{m}$. What is the potential difference between two points on the wire separated by $25 \mathrm{cm}$?

In a potentiometer experiment, the balancing length with a cell is at length $240 \mathrm{cm}$. On shunting the cell with a resistance of $2 \mathrm{\Omega }$, the balancing length becomes $120 \mathrm{cm}.$ The internal resistance of the cell is

Sensitivity of a particular potentiometer can be increased by

In a metrebridge, copper strips are used to

In potentiometer experiment, a cell is balanced by length $120 \mathrm{cm}.$ When a cell is shunted by resistance of $5 \mathrm{\Omega }$ the balancing length is $80 \mathrm{cm}.$ The internal resistance of cell is

A $2.0 \mathrm{V}$ potentiometer is used to determine the internal resistance of a $1.5 \mathrm{V}$ cell. The balance point of the cell in open circuit is $75 \mathrm{cm}$. When a resistor of $10 \mathrm{\Omega }$ is connected across the cell, the balance point shifts to $60 \mathrm{cm}$. The internal resistance of the cell is

Assertion: We prefer a potentiometer with a longer bridge wire.

Reason: By doing this, the sensitivity of the bridge is increased because for longer wire potential drop per unit length will be small.

Assertion: To compare the e.m.fs. of two cells using a potentiometer, the e.m.f. of the cell in auxiliary circuit must be greater than the e.m.fs. of both the cells.

Reason: The area of the cross-section of the wire should be uniform and current through the wire should always be kept constant.