Question

A 100 V battery is connected across a resistor and causes a current of 5mA to flow. Determine

the resistance of the resistor. If the voltage is now reduced to 25 V, what will be the new value
of the current flowing?

Answer 1

R = 20000 ohms

I = 1.25 mA

Step-by-step explanation:

From the question,

V = IR................... Equation 1

Where V = Voltage, I = Current, R = Resistance.

Make R the subject of the equation

R = V/I............... Equation 2

Given: V = 100 V, I = 5 mA = 0.005 A

Substitute into equation 2

R = 100/0.005

R = 20000 ohms.

If the Voltage is reduced to 25 V,

I = V/R.................. Equation 3

Given: V = 25 V, R = 20000 ohms.

Substitute these values into equation 3

I = 25/20000

I = 1.25 mA