Question

When 40V battery is connected across an unknown resistor there is a current of 100mA in the circuit . Find the value of the resistance of the resistor: A)5000ohm. B)800ohm. C)0.8ohm. D)400ohm

Answer 1

I mA = 0.001 A ; 100mA =100*0.001 = 0.1A

Resistance = voltage / current
= 40/0.1
= 400 ohm

The correct option is d)400 ohms

Answer 2

Answer:

R = 400 ohms

Explanation:

Given that,

Voltage of the battery, V = 40 V

Current in the unknown resistor, $I=100\ mA=10^{-1}\ A$

Let R is the resistance of the resistor. It can be calculated using Ohm's law as :

$V=I\times R$

$R=\dfrac{V}{I}$

$R=\dfrac{40\ V}{10^{-1}\ A}$

R = 400 ohms

So, the value of the resistance of the resistor is 400 ohms. Hence, this is the required solution.