Question

A coil develops heat of 800 call sec. When 20 volts is applied across its ends. The resistance of the coil is (1 cal = 2. 2 joule)

• A. $1.2\Omega$
• B. $1.4\Omega$
• C. $0.12\Omega$
• D. $0.14\Omega$

Answer 1

The correct option is A $1.2\Omega$

It is known that :

Heat produced $H=\frac{V^{2}t}{4.2R}$

According to question:

$800\times 2.2=\frac{{20}^2}{4.2R}$

$R=1.2\Omega$