The internal resistance of primary cell is 4Ω. It generates a current of 0.2 A in an external resistance of 21Ω. The rate at which chemical energy is consumed is providing the current is

 

1.  0.42 J/s

2.  0.24 J/s

3.  5 J/s

4.  1 J/s

 

There are four point charges +q, -q, +q and –q are places at the corners A, B, C and D respectively of a square of side a. The potential energy of the system is times . 

 

1.  

The potential difference across the 3Ω resistor shown in figure is 

 

1.  zero

There are N cells in the circuit of figure. The emf and internal resistance of each cell is E and rrespectively. The points A and B in the circuit divide the curit into n and (N-n) cells. The current in the circuit is

1.  E/r

The earth’s magnetic field at a certain place has ahorizontal component of 0.3 G and total strength 0.5 G. Find angle of dip in tan^-1.

 

1.  δ =tan^-1

The two spherical conductor A and B. of radii a and b(b>a) are placed concentrically in air. The two arc connected by a copper wire as shown in figure. The equivalent capacitance of the system is

 

1.  

The thermo emf of a thermocupule varies with the temperature θ of the hot junction as 
E= aθ +bθ² volt Where the ratio (a/b) is 700 °C. If the cold junction is kept at 0 °C, then the neutral temperature is

 

1.  700 °C

The wire shown in figure carries a current of 32 A. If r =3.14 cm, the magnetic field at point P will be 

 

 

1.  1.6×10^-4T

Carbon, silicon and germanium are semiconductors having four valance electrons. If their respective band gap energies between conduction and valence band are (Eg)_C, (Eg)_Si, (Eg)_Ge. Then

 

1.  (E_g)_Si<(E_g)_Ge< (E_g)_C