Two wires of equal diameters, of resistivities ${\rho _1}$ and ${\rho _2}$ and lengths $l_1$ and $l_2$, respectively, are joined in series. The equivalent resistivity of the combination is
  • A$\frac{{{\rho _1}{l_1} + {\rho _2}{l_2}}}{{{l_1} + {l_2}}}$
  • B$\frac{{{\rho _1}{l_2} + {\rho _2}{l_1}}}{{{l_1} - {l_2}}}$
  • C$\frac{{{\rho _1}{l_2} + {\rho _2}{l_1}}}{{{l_1} + {l_2}}}$
  • D$\frac{{{\rho _1}{l_1} - {\rho _2}{l_2}}}{{{l_1} - {l_2}}}$
Medium
art

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.*

Similar Questions

  • 1
    If the potential difference between $B$ and $D$ is zero, the value of $x$ is $\frac{1}{n} \Omega$. The value of $n$ is .......
    View Solution
  • 2
    In the circuit shown below, the key is pressed at time $t=0$. Which of the following statement(s) is(are) true?

    ($A$) The voltmeter displays $-5 \mathrm{~V}$ as soon as the key is pressed, znd displays $+5 \mathrm{~V}$ after a long time

    ($B$) The voltmeter will display $0 \mathrm{~V}$ at time $t=\ln 2$ seconds

    ($C$) The current in the ammeter becomes $1 / e$ of the initial value after $1$ second

    ($D$) The current in the ammeter becomes zero after a long time

    View Solution
  • 3
    Carbon resistor has resistance specified by three bands having colours red, yellow and black. If the resistor is remolded to make a resistor twice of previous length, the new colour code will be
    View Solution
  • 4
    An electric bulb of $100\, watt$ is connected to a supply of electricity of $220\, V$. Resistance of the filament is ............. $\Omega$
    View Solution
  • 5
    After switch is closed, current drawn from the battery is (in $A$)
    View Solution
  • 6
    A wire of length ' $r$ ' and resistance $100 \Omega$ is divided into $10$ equal parts. The first $5$ parts are connected in series while the next $5$ parts are connected in parallel. The two combinations are again connected in series. The resistance of this final combination is:
    View Solution
  • 7
    Three identical resistances $A$, $B$ and $C$ are connected as shown in the given figure. The heat produced will be maximum
    View Solution
  • 8
    Two batteries of different $e.m.f.'s$ and internal resistance connected in series with each other and with an external load resistor. The current is $3.0 \,A$. When the polarity of one battery is reversed, the current becomes $1.0 \,A$. The ratio of the $e.m.f.'s$ of the two batteries is ............
    View Solution
  • 9
    Two identical fuses are rated at $10\,A$. If they are joined
    View Solution
  • 10
    The potential difference between $A$ and $B$ in the Figure is .............. $V$
    View Solution