Consider a block of conducting material of resistivity shown in the figure. Current I enters at A and leaves from D. We apply the superposition principle to find voltage  developed between B and C. The calculation is done in the following steps:

(i) Take current I entering from A and assume it to spread over a hemispherical surface in the block.

(ii) Calculate field E(r) at distance r from A by using Ohm’s law  where j is the current per unit area at r.

(iii) From the r dependence of E(r), obtain the potential V(r) at r.

(iv) Repeat (i), (ii) and (iii) for current I leaving and superpose results for A and D.

For current entering at A, the electric field at a distance r from A is

Anonymous User Physics Current Electricity 10 Apr, 2020 1 Answer 61 views

Consider a block of conducting material of resistivity shown in the figure. Current I enters at A and leaves from D. We apply the superposition principle to find voltage  developed between B and C. The calculation is done in the following steps:

(i) Take current I entering from A and assume it to spread over a hemispherical surface in the block.

(ii) Calculate field E(r) at distance r from A by using Ohm’s law  where j is the current per unit area at r.

(iii) From the r dependence of E(r), obtain the potential V(r) at r.

(iv) Repeat (i), (ii) and (iii) for current I leaving and superpose results for A and D.

 measured between B and C is

Anonymous User Physics Current Electricity 10 Apr, 2020 1 Answer 70 views


A material B has twice the specific resistance of A. A circular wire made of B has twice the diameter of a wire made of A. Then for the two wires to have the same resistance, the ratio l/ lA of their respective lengths must be

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In a Wheatstone’s bridge, three resistance P, Q and R connected in the three arms and the fourth arm is formed by two resistance S1 and S2 connected in parallel. The condition for bridge to be balanced will be

Anonymous User Physics Current Electricity 10 Apr, 2020 1 Answer 63 views



Two sources of equal emf are connected to an external resistance R. The internal resistances of the two sources are R1 and R2 (R2 > R1). If the potential difference across the source having internal resistance R2 is zero, then

Anonymous User Physics Current Electricity 10 Apr, 2020 1 Answer 67 views


In a metre bridge experiment null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X < Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X against Y?

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An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of 4/3 and 2/3, then what will be the ratio of the currents passing through the wire?

Anonymous User Physics Current Electricity 10 Apr, 2020 1 Answer 64 views



The behaviour of a real gas is usually depicted by plotting compressibility factor Z versus P at a constant temperature. At high temperature and high pressure, Z is usually more than one. This fact can be explained by van der Waals equation when

Anonymous User Chemistry 09 Apr, 2020 1 Answer 92 views

















The length of a wire of a potentiometer is 100 cm, and the e.m.f. of its standard cell is E volt. It is employed to measure the e.m.f. of a battery whose internal resistance is  If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is

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The ionisation energy of solid NaCl is 180 kcal/mol. The dissolution of the solid in water is endothermic to the extent of 1 kcal per mol. If the solvation energies of Na+ and Cl– ions are in the ratio 6:5, what is the enthalpy of hydration of sodium ion

Anonymous User Chemistry 07 Apr, 2020 1 Answer 65 views

At 88°C benzene has a vapour pressure of 900 torr and toluene has a vapour pressure of 360 torr. What is the mole fraction of benzene in mixture with toluene that will boil at 88°C at 1 atm pressure assuming ideal solution.

Anonymous User Chemistry 07 Apr, 2020 1 Answer 241 views


Salts of A (atomic weight 7), B (atomic weight = 27) and C (atomic weight 48) were electrolysed under identical conditions using same quantity of electricity. It was found that when 2.1g of A was deposited, weights of B and C deposited were 2.7g and 7.2g. The valencies of A, B and C are respectively.

Anonymous User Chemistry 07 Apr, 2020 1 Answer 85 views