In a discharge tube, the number of hydrogen ions drifting across a cross-section per second is $n_{1}n\_1$ while the number of electrons drifting in the opposite direction across another cross section is $n_{2}n\_2$. If the supply voltage is V, the effective resistance, of the tube is

A one-meter-long metallic wire is broken into two unequal parts P and Q. P part of the wire is uniformly extended into another wire R. Length of R is twice the length of P and resistance of R is equal to that of Q. The ratio of the resistance of P and R, is

In a large building, there are 15 bulbs of 40 W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1 kW. The voltage of the electric mains is 220 V. The minimum capacity of the main fuse of the building will be:

When 5V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is $25\times 10^{-4}m{s}^{-1}\mathrm{.}25\; \backslash times\; 10\; ^\{-4\}\; ms\; ^\{-1\}.$ If the electron density in the wire is $8\times 10^{28}8\; \backslash times\; 10\; ^\{28\}$ $m^{-3}m\; ^\{-3\}$ the resistivity of the material is close to

The temperature dependence of resistances of Cu and undoped Si in the temperature range 300-400K, is best described by:

A conductor contains $8\times 10^{28}8\backslash times10^\{28\}$ free electrons per cubic meter. The conductor carries a current of 1A and has a length of 10 cm. The area of cross-section of the conductor is $7.81\times 10^{-6}{m}^2\mathrm{.}7.81\; \backslash times\; 10\; ^\{-6\}\; m^2.$ The time taken by an electron to move from one end of the conductor to the other end is

An electric tea kettle has two heating coils. When one of coils is switched on, the kettle begins to boil in 6 minutes. When the other is switched on the kettle begin to boil in 8 minutes. It boil the coils are switched on simultaneously and connected in parallel then the kettle will begin to boil in.

A nichrome Filament heater consumes 100W power at $27^{\circ }C27^\backslash circ\; C$, when it is used its temperature rises to $3027^{\circ }C3027^\backslash circ\; C$, the power consumed by it at the moment when switch is, put on, voltage remaining same. Given the temperature coefficient of resistively of nichrome is $4\times 10^{-4}{K}^{-1}\mathrm{.}4\; \backslash times\; 10\; ^\{-4\}\; K\; ^\{-1\}.$

Two conductors, one solid and other hollow are made up of same material, the length of solid conductor is twice the length of hollow conductor and diameter is D, while the outer diameter of hollow conductor is 2D and inner is D, the ratio of resistance between the ends of two conductors will be

The electron in a hydrogen atom moves in a circular orbit of radius $5\times 10^{-11}m5\; \backslash times\; 10\; ^\{-11\}\backslash ,m$ with a speed of $0.6\pi \times 10^{6}m\mathrm{/}s,0.6\; \backslash pi\; \backslash times\; 10\; ^6\; \backslash ,m/s\; ,$ then