Automotive Engine Auxiliary Systems Questions and Answers – Exhaust System – Mufflers

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This set of Automotive Engine Auxiliary Systems Multiple Choice Questions & Answers (MCQs) focuses on “Exhaust System – Mufflers”.

1. What pressure does an exhaust gases have?
a) Medium level pressure
b) Low pressure
c) No pressure
d) High pressure
View Answer

Answer: d
Explanation: When the exhaust valve opens, the high-pressure exhaust gas is released, which causes a pressure wave in the air causing an explosion.
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2. What is the low-frequency note of an exhaust gas?
a) 50 to 500Hz
b) 5 to 10Hz
c) 3000 to 10000Hz
d) 30000 to 200000Hz
View Answer

Answer: a
Explanation: The predominant notes out of these have been found in two groups, viz, low-frequency notes from 50 to 500Hz, and high-frequency notes from 3000 to 10000Hz.

3. What is the high-frequency note of an exhaust gas?
a) 50 to 500Hz
b) 5 to 10Hz
c) 3000 to 10000Hz
d) 30000 to 200000Hz
View Answer

Answer: c
Explanation:Exhaust gases have a very high temperature and pressure, when this strikes the walls of the exhaust system, they produce a high-frequency notes from 3000 to 10000Hz.

4. Which part is connected to the engine exhaust via an exhaust pipe,to reduce the noise?
a) Silencer
b) Valve
c) Header
d) Manifold
View Answer

Answer: a
Explanation:To reduce the noise, the engine exhaust is connected via an exhaust pipe to the silencer, which is also called muffler. Muffler reduces noise by canceling the waves.
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5. To which part a tailpipe carries the exhaust gas to the rear side near wheels?
a) Valve
b) Header
c) Manifold
d) Muffler
View Answer

Answer: d
Explanation: A tailpipe carries the exhaust gases from the muffler to the rear or side of the vehicle near the wheel. Muffler reduces noise by canceling the waves.
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6. Which of the mentioned below is not a type of muffler?
a) Baffle type
b) Resonance type
c) Light type
d) Absorber type
View Answer

Answer: c
Explanation: Baffle type, Wave cancellation type, Resonance type, Absorber type, and Combined resonance and absorber type are all the types of mufflers. Whereas light type is not a muffler.

7. Which is the major drawback of the baffle type of muffler?
a) Restriction of exhaust gas
b) Free flow of exhaust gas
c) Wave cancellation
d) Reduced noise
View Answer

Answer: a
Explanation: The major drawback of the baffle muffler is their low efficiency. Because of the restriction provided to the flow by the baffles, the backpressure is increased thus causing a loss in engine power.
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8. In which type of muffler crest of one wave coincide with the trough of the second wave?
a) Baffle type
b) Wave cancellation type
c) Resonance type
d) Absorber type
View Answer

Answer: b
Explanation: In wave cancellation type, the length of these paths is so adjusted that after they come out of the muffler, the crest of one wave coincides with the trough of the second wave, thus reducing noise.

9. What is the other name of resonance type muffler?
a) Mizer type
b) Max type
c) Helmholtz type
d) Heisenberg type
View Answer

Answer: c
Explanation: Resonance type muffler is also called a Helmholtz type, after the person who originated the idea. It consists of several Helmholtz resonators in series.
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10. In which type of muffler series of resonators are connected?
a) Baffle type
b) Wave cancellation type
c) Resonance type
d) Absorber type
View Answer

Answer: c
Explanation: Resonance type muffler is also called a Helmholtz type, after the person who originated the idea. It consists of several Helmholtz resonators in series. Series of resonators eliminate the fundamental and higher harmonics of the engine noise.

11. In which type of muffler fiberglass is used?
a) Baffle type
b) Wave cancellation type
c) Resonance type
d) Absorber type
View Answer

Answer: d
Explanation: In absorber type muffler, the sound-absorbing material, usually fiberglass, is placed in this case around the perforated tube through which the exhaust gases pass.

12. Which type of mufflers are called as glass packed mufflers?
a) Baffle type
b) Wave cancellation type
c) Resonance type
d) Absorber type
View Answer

Answer: d
Explanation: In absorber type muffler, the sound is reduced by conversion into heat by sound-absorbing material. Such mufflers are commonly known as glass packed mufflers.

13. Combined resonance and absorber type muffler has sound-absorbing material in it?
a) True
b) False
View Answer

Answer: a
Explanation: Combined resonance and absorber type muffler is a combination of both resonance and absorber type. This contains fiberglass as a noise absorbing material.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter