b specific resistance is a property of a material and it will increase with the increase of temperature, but will not vary with the dimensions (length, crosssection) of the conductor
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Two electric bulbs marked $40\,W,$ $220\,V$ and $60\,W,\,\,220\,V$ when connected in series across same voltage supply of $220\,V,$ the effective power is $P_1$ and when connected in parallel, the effective power is $P_2.$ Then $\frac {P_1}{P_2}$ is
When the current $i$ is flowing through a conductor, the drift velocity is $v$. If $2i$ current is flowed through the same metal but having double the area of cross-section, then the drift velocity will be
A potentiometer circuit shown in the figure is set up to measure $e.m.f.$ of a cell $E$. As the point $P$ moves from $X$ to $Y$ the galvanometer $G$ shows deflection always in one direction, but the deflection decreases continuously until $Y$ is reached. In order to obtain balance point between $X$ and $Y$ it is necessary to
A $10\,m$ long potentiometer wire has a potential gradient of $0.0025\, V/cm$. Calculate the distance of null point when the wire is connected to a $1.025\,V$ standard cell ............... $\mathrm{m}$
A heater $A$ gives out $300\, W$ of heat when connected to a $200\, V$ $d.c.$ supply. Asecond heater $B$ gives out $600\, W$ when connected to a $200\,v$ $d.c$. supply. If a series combination of the two heaters is connected to a $200\, V$ $d.c$. supply the heat output will be ................. $W$
Two wires of the same dimensions but resistivities ${\rho _1}$ and ${\rho _2}$ are connected in series. The equivalent resistivity of the combination is
Which of the following will NOT be observed when a multimeter (operating in resistance measuring mode) probes connected across a component, are just reversed?
The circuit below is used to heat water kept in a bucket. Assuming heat loss only by Newton's law of cooling, the variation in the temperature of the water in the bucket as a function of time is depicted by
In the arrangement shown in figure when the switch $S_2$ is open, the galvanometer shows no deflection for $l = L/2$. When the switch $S_2$ is closed, the galvanometer shows no deflection for $l = 5L /12$ . The internal resistance $(r)$ of $6\, V$ cell, and the $\mathrm{emf}$ $E$ of the other battery are respectively