# Ohm’s law – problems and solutions

1.

Based on the table below, the relation between voltage (V), electric current (I) and resistance (R) is…..

Solution :

Ohm’s law :

V = I R or R = V / I

R_{1} = V / I = 1.50 / 0.08 = 18.75 Ohm

R_{2} = V / I = 2.80 / 1.50 = 2.87 Ohm

R_{3 }= V / I = 3.99 / 2.10 = 1.9 Ohm

Based on the table, the relationship between V, I and R is the value of R inversely proportional to V and I. That means the larger the V and I, the smaller R.

The value of V / I is not constant so it does not illustrate Ohm’s law. According to Ohm’s law, the value of V / I must be constant.

2. Which graph indicates the relationship between the potential difference with the electric current?

Solution :

A

3. Based on the data in the following table of the experiment result, it can be concluded that the electric current …

Solution :

Based on the data in the table, the greater the electrical voltage, the greater the electric current. Therefore it is concluded that the electric current is proportional to the voltage.

4. A device has a 150 Ohm resistance and a 2A electric current passes. The potential difference is…

__Known :__

Resistance (R) = 150 Ohm

The electric current (I) = 2 Ampere

__Wanted:__ Voltage (V)

__Solution :__

V = I R

*V = electric voltage, I = electric current, R = electric resistance*

Voltage :

V = I R = (2 Ampere)(150 Ohm) = 300 Volt

5. The electric current in a resistor wire is 4 A. When both ends are given a potential of 12 Volts. What is the electrical resistance?

__Known :__

Electric current (I) = 4 Ampere

Voltage (V) = 12 Volt

__Wanted :__ Electric resistance (R)

__Solution :__

Resistance :

R = V / I = 12 Volt / 4 Ampere = 3 Ohm