BharatNotes Cathode
nounUsage in a UPSC answer
Just as a cathode quietly draws current to the point where reduction occurs, an effective grievance-redressal mechanism must function as the institutional terminal at which accumulated public discontent is received and resolved, rather than allowed to discharge disruptively elsewhere.
Synonyms
Antonyms
Word Family
cathode (n), cathodic (adj), cathode-ray (n compound), cathodically (adv), catholyte (n)
Root
Greek kathodos (κάθοδος) = way down/descent; kata = down; hodos = way/path; coined by Faraday 1834 on Whewell's advice
Etymology
From Greek kathodos (κάθοδος, "way down, descent"), from kata ("down") + hodos ("way, path"); coined by Michael Faraday in 1834 on the advice of William Whewell, referring to the path that cations take "downward" to the electrode.
Memory Hook
"Cat-hode" sounds like the "way DOWN" path the Greek 'kathodos' describes - and a CAThode attracts CATions (positive ions) that descend onto it during reduction.
How This Word Works in UPSC Writing
The electrode at which reduction occurs. The definition is independent of polarity and that is precisely the trap, because the cathode is the positive terminal in a galvanic cell and the negative terminal in an electrolytic cell, so anyone who memorises a sign rather than the process will answer half the questions wrongly. The rule that survives both cases is that reduction always occurs at the cathode and oxidation at the anode, whatever the sign, and cations always migrate towards the cathode. The reason polarity reverses is the direction of energy flow: a galvanic cell converts chemical energy to electrical energy spontaneously, so its cathode draws electrons from the external circuit and is positive, whereas an electrolytic cell has current forced through it by an external source, which pushes electrons onto the cathode and makes it negative. In a rechargeable cell the electrode names are conventionally fixed by the discharge direction, which is why the electrode called the cathode hosts oxidation while charging.
Don’t Confuse It With
The cathode is where reduction occurs and the anode where oxidation occurs, in every cell and regardless of polarity. In a galvanic or voltaic cell the reaction is spontaneous and the cathode is positive, while in an electrolytic cell current is supplied externally and the cathode is negative. Cations are positive ions migrating to the cathode and anions negative ions migrating to the anode. In a rechargeable cell the electrode labels are fixed by the discharge direction, which is why they appear to invert on charging.
Hindi Meaning
कैथोड; ऐनोड for anode, अपचयन (apachayan) for reduction and उपचयन for oxidation.
Common Questions
- Is the cathode positive or negative?
- It depends on the cell: positive in a galvanic cell and negative in an electrolytic one. What never changes is that reduction occurs at the cathode.
- Why do the electrode names seem to swap when a battery is charged?
- Because the labels are conventionally fixed by the discharge direction, so on charging the electrode still called the cathode is actually the site of oxidation.
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