Which combination of the following statements about direct resistance heating are correct? i) The process requires the charge to be electrically conductive. ii) Electrodes are placed in direct contact with the charge. iii) Heat is generated by induced eddy currents in the charge. iv) The charge does not form part of the electric circuit.
(i) and (ii) only
The question asks about direct resistance heating and which statements correctly describe this process. Let's analyze each given statement:
- The process requires the charge to be electrically conductive. This statement is true. In direct resistance heating, the electric current must pass through the material (charge), which implies that the charge has to be electrically conductive.
- Electrodes are placed in direct contact with the charge. This statement is also true. In direct resistance heating, electrodes are in direct contact with the charge, which allows current to flow directly through the charge, heating it up due to resistance.
- Heat is generated by induced eddy currents in the charge. This statement is incorrect in the context of direct resistance heating. Eddy currents are associated with induction heating, not direct resistance heating.
- The charge does not form part of the electric circuit. This statement is incorrect. In direct resistance heating, the charge is part of the electric circuit, which is necessary for current to pass through it and generate heat.
Based on this analysis, the correct combination of statements that describe direct resistance heating is:
- (i) The process requires the charge to be electrically conductive.
- (ii) Electrodes are placed in direct contact with the charge.
Thus, the correct answer is (i) and (ii) only.
This choice eliminates the other options because they either include incorrect statements or omit the correct ones.
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