Question

A small electronic device is rated at 0.16 W when connected to 115 V. What is the resistance of this device?

Answer 1

Answer:

150156.25 Ω

Explanation:

Resistance: This can be defined as the opposition to the flow of electric current in a circuit. The S.I unit of resistance is Ohm's (Ω)

The expression for resistance is given as

P = V²/R................ equation 1

Where P = power, V = Voltage, R = Resistance.

Making R the subject of the equation,

R = V²/P.................. Equation 2

Given: V = 115 V , P = 0.16 W.

Substitute into equation 2

R = 155²/0.16

R = 150156.25 Ω

Hence,

The resistance = 150156.25 Ω

Answer 2

Answer:

82.656 KΩ

Explanation:

The power rating (P) in a device is related to its voltage (V) and its resistance (R) as follows;

P = $\frac{V^{2} }{R}$    ------------------------(i)

Where, according to the question;

P = 0.16W

V = 115V

R is unknown

Substitute the values of P and V into the equation (i);

=> P = $\frac{V^{2} }{R}$

=> 0.16 = $115^{2}$ / R

Make R subject of the formula

=> R = $\frac{115^{2} }{0.16}$

=> R = 13225 / 0.16

=> R = 82656.25Ω

=> R = 82.656KΩ

The resistance of the device is R = 82.656KΩ