Final answer:
To correct undercutting in arc welding, reducing the current is the correct adjustment as it decreases the energy and heat input to avoid excessive melting that causes undercutting. Lengthening the arc or increasing amperage would worsen the problem.
Step-by-step explanation:
When dealing with the issue of undercutting while arc welding, it is essential to understand what causes it in order to rectify the problem. Undercutting is a groove that forms at the toe of the weld and can be a result of too high a welding current or too long an arc.
To correct undercutting, one would most likely need to adjust the welding parameters. The best choice from the options provided would be:
Reducing the current can help because it decreases the energy and heat input into the material, reducing the chances of excessive melting and therefore avoiding the undercut. Adjustments such as lengthening the arc, using longer electrodes, or switching to a higher amperage would generally exacerbate the problem rather than correct it.
In relation to the reference information provided about circuits, to increase the power you would choose:
- b. reduce the resistance to increase the power
Power in a circuit is directly related to the square of the current multiplied by the resistance (P = I^2 * R). Hence, reducing the resistance, with current staying constant, increases the power dissipated.