Question

Calculate the power used in the 2ohm resistor in each of the following circuits:[Applying] a) a 6V battery in series with 1ohm and 2 ohm resistors. b) a 4V battery in parallel with 12 ohm and 2 ohm resistors. 3. (a) State and explain Joule’s law of heating.​

Answer 1

Explanation:

a) series ckt potential divides in the ratio of resistances

1:2

∴ p.d a cross 2 Ω resistor V₂ = 2/3 x 6 = 4 V

power in 2Ω resistor = V₂²/R₂ = 16/2 = 8 W

b) Since parallel combination,

p.d a cross 2 Ω resistor V₂ = 4V

power in 2Ω resistor = V₂²/R₂ = 16/2 = 8 W

c) Joule's law of heating :

statement : It states that heat dissipated in an electric circuit is directly proportional to

I) square of the current (I²)

ii) resistance of the conductor (R)

iii) time for which current flows (t)

Heat dissipated H = I²Rt (in joules)