Embibe Experts Solutions for Chapter: Current Electricity, Exercise 3: Level 3

In a semiconductor, mobility of electron, i.e., drift velocity per unit applied electric field is $1.6$ ($\text{S.Ι.}$ unit). The density of electron is ${10}^{19} {\mathrm{m}}^{-3}$ (Neglect holes concentration). The resistivity of semiconductor is $n \mathrm{\Omega } \mathrm{m}$. Write the value of $10n$ to the nearest integer.

What is the charge (in $\mathrm{C}$) that passes through the cross-section of a wire in the time interval $t=3\mathrm{ }\mathrm{s}$ to $t=5\mathrm{ }\mathrm{s}$, when it is known that current in the wire is given by the equation $I=2t^2-3t+1$? (Approximate the answer to the nearest integer)

What is the current in the $4 \mathrm{\Omega }$ resistor when switch $S_1$ is open and switch $S_2$ is closed in the given circuit?

A strip of copper and another of germanium are cooled from room temperature to $80 \mathrm{K}.$ The resistance of 

A potential difference of $5 \mathrm{V}$ is applied across a conductor of length $0.1 \mathrm{m}$. If the electron mobility is $5\times {10}^{-6}{ \mathrm{m}}^2{\mathrm{v}}^{-1}{\mathrm{s}}^{-1}$ then the drift velocity of electron is

In the given circuit find reading of ammeter (in A) when capacitor has attained steady state. (Approximate the answer to the nearest integer)

One of the circuits for the measurement of resistance by potentiometer is shown. The galvanometer is connected at point $A$ and zero deflection is observed at length $PJ=30 \mathrm{cm}.$ In second case the secondary cell is changed. Take $E_S=10 \mathrm{V}$ and $r=1\mathrm{\Omega }$ in $1^{\mathrm{st}}$ reading and $E_S=5 \mathrm{V}$ and $r=2\mathrm{\Omega }$ in $2^{\text{nd }}$ reading. In second case, the zero deflection is observed at length $PJ=10 \mathrm{cm}$. What is the resistance $R$ (in ohm)?

The maximum current in a galvanometer can be $10 \mathrm{mA}$. It's resistance is $10\mathrm{\Omega }$. To convert it into an ammeter of $1 \mathrm{Amp}$. a resistor should be connected in