A coil develops heat of $800\, cal/sec$. When $20\, volts$ is applied across its ends. The resistance of the coil is .............. $\Omega$ ($1$ $cal$ = $4.2$ $joule$)
Medium
Download our app for free and get started
(c) $H = \frac{{{V^2}t}}{{4.2\,R}}$ or $\frac{H}{t} = \frac{{{V^2}}}{{4.2\,R}}$
$ \Rightarrow $ $800 = \frac{{20 \times 20}}{{4.2 \times R}}$$ \Rightarrow $$R = \frac{5}{{42}} = 0.119 \approx 0.12\,\Omega $
$ \Rightarrow $ $800 = \frac{{20 \times 20}}{{4.2 \times R}}$$ \Rightarrow $$R = \frac{5}{{42}} = 0.119 \approx 0.12\,\Omega $
Download our appand 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.*
Similar Questions
- 1The length of a metallic wire is increased by $20 \%$ and its area of cross section is reduced by $4 \%$. The percentage change in resistance of the metallic wire is $.......$View Solution
- 2Given below are two statements:View Solution
Statement $I$ : A uniform wire of resistance $80\,\Omega$ is cut into four equal parts. These parts are now connected in parallel. The equivalent resistance of the combination will be $5\,\Omega$.
Statement $II :$ Two resistance $2\,R$ and $3\,R$ are connected in parallel in a electric circuit. The value of thermal energy developed in $3\,R$ and $2\,R$ will be in the ratio $3:2.$
In the light of the above statements, choose the most appropriate answer from the options given below
- 3In the given circuit all resistances are of value $R\,ohm$ each. The equivalent resistance between $A$ and $B$ isView Solution
- 4In the circuit shown in figure, the power which is dissipated as heat in the $6\,\Omega$ resistor is $6\,W$. What is the value of resistance $R$ in the circuit?................... $\Omega$View Solution
- 5Two electric bulbs whose resistances are in the ratio of $1 : 2$ are connected in series. The powers dissipated in them have the ratioView Solution
- 6View SolutionConsider four circuits shown in the figure below. In which circuit power dissipated is greatest (Neglect the internal resistance of the power supply)
- 7For a wire $\frac{R}{l}=\frac{1}{2}$ and length of wire is $l=5\, cm .$ If potential difference $1\, V$ is applied across it, current through wire will be: $( R =$ Resistance $)$ (in $A$)View Solution
- 8In the circuit shown, the point ‘$B$’ is earthed. The potential at the point ‘$A$’ is ............. $V$View Solution
- 9A bulb of $100\, W$ is connected in parallel with an ideal inductance of $1\, H$. This arrangement is connected to a $90\,V$ battery through a switch. On pressing the switch, theView Solution
- 10In a metre-bridge when a resistance in the left gap is $2\ \Omega$ and unknown resistance in the right gap, the balance length is found to be $40\ \mathrm{~cm}$. On shunting the unknown resistance with $2\ \Omega$, the balance length changes by :View Solution