Question

The power dissipated in the circuit shown in the figure is 30 Watts. The value of R is(a) 20 Ω(b) 15 Ω(c) 10 Ω(d) 30 Ω

Answer 1

(c) 10 omh is the answer. here is the full explanations. hope this helps you and pls mark me as brainliest

Answer 2

Given that,

The power dissipated in the circuit shown in the figure is 30 Watts.

To find,

The value of R.

Solution,

We can see from the attached figure that two resistors of resistances R and 5 ohms are connected in parallel. The equivalent resistance in this case is given by :

$\dfrac{1}{R'}=\dfrac{1}{R_1}+\dfrac{1}{R_2}\\\\\dfrac{1}{R'}=\dfrac{1}{R}+\dfrac{1}{5}\\\\\dfrac{1}{R'}=\dfrac{5+R}{5R}\\\\R'=\dfrac{5R}{5+R}$

We know that, the power dissipated is given by :

$P=\dfrac{V^2}{R'}$

We have, P = 30 Watts

$30=\dfrac{(10)^2}{\dfrac{5R}{5+R}}\\\\30=\dfrac{100}{\dfrac{5R}{5+R}}\\\\3=\dfrac{10}{\dfrac{5R}{5+R}}\\\\150R=100(5+R)\\\\150R=500+100R\\\\50R=500\\\\R=10\ \Omega$

So, the value of R is 10 ohms.