Question

. A wire of resistance 25Ω is made of manganin alloy and is connected across a car battery of 12V emf and negligible internal resistance. How much heat energy is produced in 30 minutes (in Joules)?

Answer 1

Answer:

by using Joules law of heating

H=I^2RT=(12/25)^2x25x900=10368 joules

Answer 2

Given :

Resistance (R) = 25 ohm

EMF (V) = 12 V

Time (T) = 30 min

To Find :

How much heat energy is produced in 30 minutes

Solution :

We know, Heat produced (H) =  $\frac{V^2}{R}$ × T

We are required to find the amount of heat produced in 30 minutes when a resistance of 25Ω is connected across a car battery of 12V.  

where, V = Potential difference; R = resistance; T = Time

Heat produced (H) = $\frac{12^2}{25}$×30×60

                               =  $\frac{144}{25}$ × 1800

                               = 10368 J

Therefore, the heat energy produced in 1 min is 10368 J.