Why are the tyres of aircrafts made of conducting rubber? 1. So that the charge accumulated on the aircraft in flight, by rubbing the air, can easily be transferred to ground on landing. 2. So that the charge accumulated due to the operation of various electronic equipments in the aircraft in flight can easily be transferred to ground on landing. Select the correct answer using the code given below.
- (a)1 only
- (b)2 only
- (c)Both 1 and 2
- (d)Neither 1 nor 2
Correct — A, 1 only. As an aircraft flies, friction between its body and the air builds up a large static electric charge. Conducting rubber tyres provide a path for this accumulated charge to leak safely to the earth the instant the aircraft touches down, preventing sparks. So statement 1 is the correct reason. Statement 2 is wrong: the onboard electronic equipment's circuits are bonded to the airframe and do not leave a net static charge for the tyres to discharge — that is not why the tyres are made conducting.
- (b)2 only — The charge that conducting tyres bleed to earth is the static charge built up by friction with the air, not charge from onboard electronics — so statement 2 is not the reason.
- (c)Both 1 and 2 — Statement 1 is correct but statement 2 is not, so 'both' is wrong.
- (d)Neither 1 nor 2 — Statement 1 is a valid reason — static charge from air friction is earthed on landing — so 'neither' is incorrect.
Rubbing two surfaces transfers electrons and leaves them charged — static electricity by friction. A fast aircraft rubbing against the air accumulates such a charge on its body. A conductor connected to the earth lets this excess charge flow away (earthing), which is exactly what conducting tyres do on touchdown.
The distractor blames onboard electronics, but their circuits are already bonded to the airframe and carry no net static charge for the tyres to remove. The charge that matters is the triboelectric charge from air friction (and from fuelling), which conducting tyres safely earth.
- Friction with air charges an aircraft's body with static electricity during flight (and refuelling).
- Conducting tyres provide a path to earth this charge on landing, preventing sparks.
- Static charge on a conductor stays on its outer surface and can be neutralised by earthing.
- The same principle underlies lightning conductors and the earthing of electrical appliances.
- Blaming onboard electronics for the static charge rather than friction with the air.
- Thinking insulating tyres would be safer — they would trap the charge instead of earthing it.
A statement-code item — conducting tyres exist to earth the friction-generated static charge on landing (statement 1 only).
No directly related past PYQ was found.
- practice — not a real PYQ
Static charge builds up on a fast-moving aircraft mainly due to
- (a)onboard batteries
- (b)friction with the air
- (c)the heat of the engines
- (d)sunlight
Answer(b) friction with the air.
- practice — not a real PYQ
Earthing a charged conductor means
- (a)increasing its charge
- (b)connecting it to the ground to transfer excess charge
- (c)insulating it completely
- (d)heating it
Answer(b) connecting it to the ground to transfer excess charge.