$A$ constant voltage is applied between the two ends of a uniform metallic wire. Some heat is developed in it. The heat developed is doubled if
A
both the length and the radius of the wire are halved.
B
both the length and the radius of the wire are doubled
C
the radius of the wire is doubled
D
the length of the wire is doubled
Medium
Download our app for free and get started
B
both the length and the radius of the wire are doubled
b Heat developed is
$H=\frac{V^{2}}{R} t$
Heat developed will be doubled when $R$ is halved. Further,
$R=\rho l /\left(\pi r^{2}\right)$ and $H=V^{2} \pi r^{2} t / \rho l .$ So heat produced when both the length and radius of the wire are doubled.
Download our app
and get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
In the circuit shown in figure, the current drawn from the battery is $4\,A$. If $10 \,\Omega$ resistor is replaced by $20\,\Omega$ resistor, then current drawn from the circuit will be .............. $A$
A battery consists of a variable number $n$ of identical cells (having internal resistance reach) which are connected in series. The terminals of the battery are short-circuited and the current $I$ is measured. Which of the graphs shows the correct relationship between $I$ and $n \,?$
A uniform metallic wire of length $L$ is mounted in two configurations. In configuration $1$ (triangle), it is an equilateral triangle and a voltage $V$ is applied to corners $A$ and $B$. In configuration $2$ (circle), it is bent in the form of a circle and the potential $V$ is applied at diametrically opposite points $P$ and $Q$. The ratio of the power dissipated in configuration $1$ to configuration $2$ is
$A$ battery consists of a variable number $n$ of identical cells having internal resistance connected in series. The terminals of the battery are short circuited and the current $I$ measured. Which one of the graph below shows the relationship between $I$ and $n$?
In a Wheatstone bridge (see figure) Resistance $P$ and $Q$ are approximately equal. When $R = 400\,\Omega ,$ the bridge is balanced. On interchanging $P$ and $Q,$ the value of $R,$ for balance is $405\,\Omega .$ The value of $X$ is close to ................. $ohm$
A $10 \,m$ long potentiometer wire is connected to a battery having a steady voltage. A Leclanche cell is balanced at $4 \,m$ length of the wire. If the length is kept the same, but its cross-section is doubled, the null point will be obtained at ........... $m$
If three resistors of resistance $2 \,\Omega$, $4 \,\Omega$ and $5 \,\Omega$ are connected in parallel then the total resistance of the combination will be