Current Calculation:
To calculate the current drawn by the heating element, we can use Ohm's law, which states that the current (I) flowing through a conductor is equal to the voltage (V) across the conductor divided by its resistance (R). Mathematically, it can be expressed as:

I = V / R

Given that the voltage across the heating element is 210V, we can substitute this value in the equation. However, we need to find the resistance of the element first.

Resistance Calculation:
The power (P) consumed by a device can be calculated using the formula:

P = V * I

Here, P is given as 630W and V as 210V. By rearranging the formula, we can solve for current:

I = P / V

Substituting the given values:

I = 630W / 210V

I = 3A

Current Drawn:
Therefore, the current drawn by the heating element when connected to a 210V DC mains is 3A.

Resistance Calculation:
Now, we can calculate the resistance of the heating element using Ohm's law:

R = V / I

Substituting the given values:

R = 210V / 3A

R = 70Ω

Explanation:
When an electrical device is connected to a power supply, it draws a certain amount of current based on its power rating and the voltage across it. In this case, the heating element is marked as 210V and 630W.

By using the power formula, we can calculate the current drawn by the heating element. Once we have the current value, we can use Ohm's law to find the resistance of the element.

Ohm's law states that the current flowing through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance. Thus, by rearranging the formula, we can solve for current and resistance.

In this scenario, the heating element draws a current of 3A when connected to a 210V DC mains. The resistance of the element is determined to be 70Ω.

It is important to note that the resistance value can help in understanding the power consumption and potential heat generation of the element. The higher the resistance, the more power it consumes and the more heat it produces.