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A hot electric iron has a resistance of $80\,\Omega $ and is used on a $200\, V$ source. The electrical energy spent, if it is used for two hours, will be ........... $Wh$
Eels are able to generate current with biological cells called electroplaques. The electroplaques in an eel are arranged in $100$ rows, each row stretching horizontally along the body of the fish containing $5000$ electroplaques. The arrangement is suggestively shown below. Each electroplaques has an emf of $0.15\, V$ and internal resistance of $0.25 \,\Omega$ The water surrounding the eel completes a circuit between the head and its tail. If the water surrounding it has a resistance of $500 \,\Omega$, the current an eel can produce in water is about .............. $A$
In the given potentiometer circuit length of the wire $AB$ is $3\,m$ and resistance is $R=4.5\,\Omega $. The length $AC$ for no deflection in galvanometer is ............... $m$
A potentiometer wire, $10\,m$ long, has a resistance of $40\,\Omega $. It is connected in series with a resistance box and a $2\,V$ storage cell. If the potential gradient along the wire is $0.1\,m\,V/cm$, the resistance unplugged in the box is .............. $\Omega$
An electric lamp is marked $60\, W$, $230\, V$. The cost of a $1\, kWh$ of energy is Rs. $1.25$. The cost of using this lamp $8$ hrs a day for $30$ day is Rs. ...............
In an electrical cable there is a single wire of radius $9\, mm$ of copper. Its resistance is $5\,\Omega $. The cable is replaced by $6$ different insulated copper wires, the radius of each wire is $3\,mm$. Now the total resistance of the cable will be ............... $\Omega$
A button battery is rated $3 \,V$ and $225 \,mAh . A$ cricket ball (mass $=0.163 \,kg$ ) having energy equal to that stored in the battety will have speed closest to ............ $\,m / s$
In the given circuit diagram, the currents, ${I_1} = - \,0.3\,A,\,{I_4} = 0.8\,A$ and ${I_5} = 0.4\,A,$ are flowing as shown. The currents $I_2,\,I_3$ and $I_6,$ respectively are