Question

When a 12V battery is connected across an unknown resistor, there is a current of 2.5mA in the circuit. Find the value of resistance of the resistor?​

Answer 1

Given

• Voltage= 12V
• Current= 2.5 mA

To find

• Resistance

Topic

• Ohm's Law

Solution

Current is given as 2.5 mA. So first we will convert Milli Ampere into Ampere

So we know that

$\sf{»1 mA = 10^{-3} \: Ampere}$

$\sf{»2.5 mA = \red{2.5 ×10^{-3} \: Ampere}}$

Now according to Ohm's Law

${\underline{\boxed{\sf{ \color{grey}{V=IR}}}}}$

where

• v denotes voltage
• I denotes current
• R denotes resistance

$\sf{⇝R= \dfrac{V}{I}}$

$\sf{⇝R=\dfrac{12}{2.5 ×10^{-3}}}$

$\sf{⇝R = \dfrac{12}{0.0025}}$

$\sf{⇝R= 4800 Ω}$

$\sf{⇝R= 4.8 ×10³ Ω}$

$\sf{⇝R= \orange{4.8 kΩ} \: \: \: \: \: \: [1 kΩ= 10³ Ω]}$

Therefore the resistance is 4.8 kΩ

----------------------------------------------------

⚘Ohm's Law : it states that the voltage across a conductor is directly proportional to the current flowing through it, provided the temperature remain constant.

⚘Ohm's Law was given by Georg Simon Ohm