**Electric Heater and Ohm's Law**

An electric heater works on the principle of Ohm's Law, which states that the current flowing through a conductor is directly proportional to the voltage across it, and inversely proportional to its resistance.

The equation that represents Ohm's Law is:

V = I * R

Where:
- V is the potential difference (voltage) across the conductor
- I is the current flowing through the conductor
- R is the resistance of the conductor

In the case of an electric heater, the resistance is constant, so we can rearrange Ohm's Law to solve for the current:

I = V / R

**Current Calculation at 60V**

Given that the potential difference across the electric heater is 60V and it draws a current of 4A, we can calculate its resistance using Ohm's Law:

R = V / I
R = 60V / 4A
R = 15Ω

Therefore, the resistance of the electric heater is 15Ω.

**Current Calculation at 120V**

Now, if the potential difference across the electric heater is increased to 120V, we can use Ohm's Law to calculate the new current:

I = V / R
I = 120V / 15Ω
I = 8A

Therefore, if the potential difference across the electric heater is increased to 120V, the heater will draw a current of 8A.

**Explanation**

When the potential difference (voltage) across an electric heater is increased, according to Ohm's Law, the current flowing through the heater will also increase if the resistance remains constant. This is because an increase in voltage will create a greater driving force for the flow of electric charges.

In this scenario, doubling the potential difference from 60V to 120V results in doubling the current from 4A to 8A. This indicates that the electric heater will draw more current, generating more heat as a result.

It is important to note that this relationship holds true as long as the resistance of the heater remains constant. If the resistance were to change, the relationship between voltage and current would also change.