current electricity class12

SI unit of current

• $Cs^{-1}$

• $C^{-1}S$

• $CS$

• $C^2S^{-1}$

Relation between electric current and mobility I=

• $enA\mu_eE$

• $\mu E$

• $neAV_d$

• $V_d\mu$

SI UNIT OF MOBILITY

• $m^2V^{-1}S^{-1}$

• ohm

• $\Omega m$

• $m^2V^2S^{-1}$

IN JUNCTION RULE,SUM OF CURRENTS AT ANY JUNCTION IS

• ZERO

• 1

• V/R

• NONE

Vector form of OHMS LAW

• V = IR

• $j^{\rightarrow}=\sigma E^{\rightarrow}$

• G=1/R

• NONE

The storage battery of a car has an emf of 12 V. If the internalresistance of the battery is 0.4 Ω, what is the maximum currentthat can be drawn from the battery?

• 20 A

• 30A

• 10A

• 100A

A silver wire has a resistance of 2.1 Ω at 27.5 °C, and a resistanceof 2.7 Ω at 100 °C. Determine the temperature coefficient ofresistivity of silver.

• $0.00394\degree C^{-1}$

• $0.000394\degree C^{-1}$

• $1.00394\degree C^{-1}$

• $0.00994\degree C^{-1}$

In a potentiometer arrangement, a cell of emf 1.25 V gives a balancepoint at 35.0 cm length of the wire. If the cell is replaced by anothercell and the balance point shifts to 63.0 cm, what is the emf of thesecond cell?

• $12.25V$

• $0.25V$

• $2.25V$

• 0V

Six lead-acid type of secondary cells each of emf 2.0 V and internalresistance 0.015 Ω are joined in series to provide a supply to aresistance of 8.5 Ω. What are the current drawn from the supply

• 11.4A

• 114A

• 1.4A

• 4A

 $\frac{R_1}{R_2}=\frac{R_3}{R_4}$  IS THE CONDITION OF BALANCED

• POTENTIOMETER

• WHEATSTONE BRIDGE
  

• OHMS LAW
  

• KIRCHOFFS RULE