At what temperature will the resistance of a copper wire become three times its value at $0\,^oC$ ................. $^oC$ (Temperature coefficient of resistance for copper = $4 × 10^{-3} \,per\, \,^oC$ )
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The three resistances $A, B$ and $C$ have values $3R, 6R$ and $R$ respectively. When some potential difference is applied across the network, the thermal powers dissipated by $A, B$ and $C$ are in the ratio
A capacitor of capacitance $5\,\mu F$ is connected to a source of constant $emf$ of $200\,V$ for a long time, then the switch was shifted to contact $2$ from contact $1$ . The total amount of heat generated in the $500\,\Omega $ resistance, thereafter is
Length of a hollow tube is $5\,m$, it’s outer diameter is $10\, cm$ and thickness of it’s wall is $5\, mm$. If resistivity of the material of the tube is $1.7 \times 10^{-8} \,\Omega m$ then resistance of tube will be
When a resistor of $11 \,\Omega$ is connected in series with an electric cell, the current flowing in it is $0.5\, A$. Instead, when a resistor of $5 \,\Omega$ is connected to the same electric cell in series, the current increases by $0.4\, A$. The internal resistance of the cell is ................ $\Omega$
A current of $6\, A$ enters one corner $P$ of an equilateral triangle $PQR$ having $3$ wires of resistance $2 \,\Omega$ each and leaves by the corner $R$. The currents $i_{1}$ in ampere is ........ .
Space between two concentric conducting spheres of radii $a$ and $b (b > a)$ is filled with $a$ medium of resistivity $\rho $. The resistance between the two spheres will be
Infinite number of cells having $emf$ and internal resistance $\left( {E,r} \right)$, $\left( {\frac{E}{n},\frac{r}{n}} \right)$, $\left( {\frac{E}{{{n^2}}},\frac{r}{{{n^2}}}} \right)$, $\left( {\frac{E}{{{n^3}}},\frac{r}{{{n^3}}}} \right)$..... are connected in series in same manner across an external resistance of $\frac{{nr}}{{n + 1}}$ . Current flowing through the external resistor is
Resistance are connected in a meter bridge circuit as shown in the figure. The balancing length $l_{1}$ is $40\,cm$. Now an unknown resistance $x$ is connected in series with $P$ and new balancing length is found to be $80\,cm$ measured from the same end. Then the value of $x$ will be $.......\Omega$
In a meter bridge experiment $\mathrm{S}$ is a standard resistance. $\mathrm{R}$ is a resistance wire. It is found that balancing length is $l=25 \;\mathrm{cm} .$ If $\mathrm{R}$ is replaced by a wire of half length and half diameter that of $\mathrm{R}$ of same material, then the balancing distance $\left.l^{\prime} \text { (in } \mathrm{cm}\right)$ will now be