Question

A heating coil is immersed in a calorimeter of heat capacity 50 joule per degree celsius containing 1 kg of a liquid of specific heat capacity 450 joule per kg per degree celsius. the temperature of the liquid rises by 10 degree celsius when 2 ampere current is passes through it for 10 minutes. Find
1. the resistance of the coil
2. the potential difference across the coil

Answer 1

Answer on Question#39068, Physics, Thermodynamics

Question:

A heating coil is immersed in a calorimeter of heat capacity 50 joule per degree Celsius containing 1 kg of a liquid of specific heat capacity 450 joule per kg per degree Celsius. The temperature of the liquid rises by 10 degree Celsius when 2 ampere current is passes through it for 10 minutes. Find

1. the resistance of the coil

2. the potential difference across the coil

Answer:

The power of electricity current equals:

$$P = I ^ {2} R = U I$$

The law conservation of energy:

$$P \Delta t = \Delta Q$$

where $\Delta t$ is time, $Q$ – changing of heat;

$$Q = (c m + C) \Delta T$$

$c$ is specific heat capacity, $C$ is heat capacity $T$ – temperature;

Therefore:

$$R = \frac {(c m + C) \Delta T}{\Delta t I ^ {2}} = 2.1 \, \Omega$$ $$U = \frac {(c m + C) \Delta T}{\Delta t I} = 4.2 \, V$$

Answer: $R = 2.1 \, \Omega, U = 4.2 \, V$