Current Electri...

The resistance of a carbon filament at $$0^oC$$ is 104$$\Omega$$. It is connected in series with an iron wire. The temperature coefficients of resistivity of carbon and iron are $$- 0.0003$$ and $$0.0052$$ per $$^oC$$ respectively. What must be the resistance of iron wire so that the combined resistance does not change with temperature?

A battery of emf $$E_0 = 12 \space V$$ is connected across a $$4m$$ long uniform wire having resistance $$4 \space\Omega/m$$. The cells of small emfs $$\epsilon_1 = 2V$$ and $$\epsilon_2 = 4V$$ having internal resistance $$2\space\Omega$$ and $$6\space\Omega$$ respectively, are connected as shown in the figure. If galvanometer shows no deflection at the point $$N$$, the distance of point $$N$$ from the point $$A$$ is equal to

In Fig. A B is 300 cm long wire having resistance $$10\Omega$$ per meter. Rheostate is set at $$20\Omega$$. The balance point will be attained at

Which of the V-I graph obeys Ohm's law?

In the circuit shown in the fig the heat produced in resistance $$R_1$$ can be measured by

Two cells of same emf are connected in series. Their internal resistances are $$r_1$$ and $$r_2$$ respectively and $$r_1 > r_2$$. When this combination is connected to an external resistance R then the potential difference between the terminals of first cell becomes zero. In this condition the value of R will bw

Three voltmeters, all having different resistances, are  joined as shown. When some potential difference is applied across A and B, their readings are $$V_1, V_2, V_3$$

The length of a potentiometer wire is 10m. The distance between the null points on its wire corresponding to two cells comes out to be 60 cm. If the difference of emf's of the cells is 0.4 volt then the potential gradient on potentiometer wire will be

On comparing the emf's $$E_1$$ and $$E_2(E_1 > E_2)$$ of two cells by a potentiometer, the balancing lengths come out to be $$l_1$$ and $$l_2$$ respectively, then

The potentiometer is more appropriate for measuring potential difference than a voltmeter because