Question

A variable resistor has a voltage of 12.0 V placed across it. If the resistance is increased 20%, what happens to the current flowing through it

Answer 1

Step-by-step explanation:

Remark

The answer is in the formula

E = I * R

• E = the voltage
• I = the Current
• R = the Resistance

Solution

Let the resistance = R

I = 12/R

If we increase the resistance by 20% then we get

R1 = R + (20/100) * R

R1 = R + 1/5 * R

R1 = 6 R/5

What happens to I when you do this

I = 12/(6/5 R) Effectively you need to treat 6/5 as a reciprocal

I = 12 * 5/6 * R

I = 10 / R

What does this tell you? Since the Resistance has a base value of R, when increased by 20%, the numerator of the fraction is reduced to 10 from 12. In other words the current is now smaller when R goes up.