A railway compartment is lit up by thirteen lamps each taking $2.1\, amp$ at $15\, volts$. The heat generated per second in each lamp will be ............ $cal$
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The following circuit consist of a $5 \,\mu F$ capacitor, having charge $50 \,\mu C$ as shown. The switch is closed at $t=0$. The value of current in $2 \,M \Omega$ resistor at $t=0$ is ........... $\mu A$
Dimensions of a block are $1\,cm \times 1\,cm \times 100\,cm$. If specific resistance of its material is $3 \times {10^{ - 7}}\,ohm - m$, the resistance between the square faces is
In the following diagram, the lengths of wires $A B$ and $B C$ are equal, but the radius of wire $A B$ is double that of $B C$. The ratio of potential gradient on wires $A B$ and on $B C$ will be (wires are made of same material)
An electric bulb rated as $200\, {W}$ at $100 \,{V}$ is used in a circuit having $200\, {V}$ supply. The resistance $'R'$ that must be put in series with the bulb so that the bulb delivers the same power is $.....\,\Omega$
What length of the wire of specific resistance $48 \times {10^{ - 8}}\,\Omega \,\,m$ is needed to make a resistance of $4.2 \, \Omega$ .............. $m$ (diameter of wire = $0.4\, mm$)
When a current of $2\,A$ flows in a battery from negative to positive terminal, the potential difference across it is $12\,V$. If a current of $3\,A$ flows in the opposite direction potential difference across the terminals of the battery is $15\,V$, the emf of the battery is ............... $\mathrm{V}$
Two batteries, one of emf $18\,volts\;emf$ and internal resistance $2\,\Omega $ and the other of emf $12\, volt$ and internal resistance $1\,\Omega $, are connected as shown. The voltmeter $V$ will record a reading of .............. $volt$
If two bulbs of wattage $25$ and $100$ respectively each rated at $220\, volt$ are connected in series with the supply of $440\, volt$, then which bulbs will fuse