A potentiometer wire has length 4 m and resistance 8 Ω. The resistance that must be connected in series with the wire and an accumulator of e.m.f. 2 V, so as to get a potential gradient 1 mV per cm on the wire is

The Kirchhoff’s first law (Σi = 0) and second law (ΣiR = ΣE), where the symbols have their usual meanings, are respectively based on

The resistance of a bulb filament is 100 Ω at a temperature of 100°C. If its temperature coefficient of resistance be 0.005 per °C, its resistance will become 200 Ω at a temperature of

A, B and C are voltmeters of resistance R, 1.5R and 3R respectively as shown in the figure. When some potential difference is applied between X and Y, the voltmeter readings are V_A, V_B and V_C respectively, then

A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be

Two cities are 150 km apart. Electric power is sent from one city to another city through copper wires. The fall of potential per km is 8 volt and the average resistance per km is 0.5 Ω. The power loss in the wire is

The thermistors are usually made of:

A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of 2.0 V and a negligible internal resistance. The potentiometer wire itself is 4 m long. When the resistance, R, connected across the given cell, has values of
(i) Infinity
(ii) 9.5 Ω,
the balancing lengths on the potentiometer wire are found to be 3 m and 2.85 m, respectively. The value of internal resistance of the cell is

In a potentiometer experiment, the balancing length with a cell is 240 cm. On shunting the cell with a resistance of 2 Ω, the balancing length becomes 120 cm. The internal resistance of the cell is

The thermo emf of a thermocouple varies with the temperature θ of the hot junction as E = aθ + bq² (in volts) where the ratio a/b is 700°C. If the cold junction is kept at 0°C, then the neutral temperature of the thermocouple is: