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Correct answer is (B) Dehumidification

To EXPLAIN I would say: The Dehumidification may be carried out by first bringing down the temperature of AIR below the Dew Point, then condensing out the required quantity of MOISTURE from it and then reheating the air with dry heat upto the desired temperature.

Correct choice is (c) Shape

The explanation is: A fan shop floor PLAN gives better performance. The concave walls are not good for acoustic purposes as they tend to concentrate sound waves. The PLAIN walls are better. But the convex walls are EXCELLENT and are used to reduce the POSSIBILITIES of equals to the minimum extend.

Correct OPTION is (a) Relative humidity

The explanation is: When a certain VOLUME of AIR at a certain temperature contents as MUCH water vapour as it can, it is said to be Saturated air. Generally, the air is not saturated at all times. But it contains a certain amount of water vapour in it.

The correct option is (b) Sonic BOOM

The best explanation: A sonic boom is very DESTRUCTIVE in nature. But the most UNFORTUNATE case is when the sound damages the DELICATE organ to receive it, namely, the human EAR. Hence, the sound pollution is a very concern problem.

The correct choice is (a) Absorbent

For explanation I would say: The interior SURFACES of WALLS in a studio should be of absorbent materials. However, the outer surfaces of the walls should be of the reflective type. Provision of windows should be minimum in ORDER to PREVENT the noise from outside.

The correct CHOICE is (c) Absorption

The BEST explanation: Some of the common acoustical DEFECTS are reverberation, the formation of echoes, exterior noise and sound foci. Absorption is the property of the sound wave by which a part of its energy is absorbed by FRICTION when it strikes a surface.

The CORRECT choice is (b) False

The EXPLANATION: A RIGID wall is comprised of stone, brick or concrete masonry plastered on one or both sides. The sound insulation offered by rigid homogenous walls depends on the weight per unit area and it decreases with the increase in the thickness of the wall.

Right answer is (d) SOUND

The best I can explain: The compression produced in the atmosphere is propagated or spread away from the source. HENCE, the Sound travels in the form of WAVES and when these waves come near over ear drums, we FEEL the sensation of hearing.

The correct option is (a) True

Explanation: Professor Sabine found that the REVERBERATION TIME is independent of the shape of the room. This time is ALSO independent of the POSITION of the SOURCE of the sound and the listener.

The CORRECT answer is (d) Ducts

Easy explanation: The ducts are to be CAREFULLY design with regard to pressure, velocity and volume of AIR. The ducts should be so shaped than located that EVEN distribution of conditioned air takes place in a room.

The CORRECT answer is (c) EXHAUST

Easiest explanation: The COMBINATION of exhaust and supply system gives better results. The exhaust fans and input fans are installed and suitable places in the outside walls so as to cause a current of FRESH air from outside to inside of the ROOM.

The correct choice is (a) AIR change

Best explanation: The minimum and maximum rates of air change per hour is 1 and 60 respectively. If the rate of change is LESS than 1/hour, it will not create any appreciable effect of the ventilation system. On the other hand, at the rate of air CHANGES more than 60/hour, it will result in discomfort due to HIGH velocities of air.

The correct option is (c) CONDENSATION

The EXPLANATION: The proper and sufficient ventilation RESULTS in the absence of condensation. It can be effectively controlled by the PROVISION of suitable ventilation of the room.

The correct answer is (C) 60 dB

For explanation I would say: Reduction in the sound intensity during the transmission of sound from the source to the adjoining area is KNOWN as transmission loss. The transmission loss is numerically EQUIVALENT to the loss in the sound intensity in decibels. Hence, it is given by 60-40 dB = 20 dB.

The correct choice is (B) False

To explain I would say: There are three PHENOMENONS that happen when SOUND waves strike the surface of a room. These are reflection, absorption and transmission. The amount of sound transmitted outside a room DEPENDS on the sound insulation properties of the surface while the amount of sound reflected or ABSORBED depends on the surface.

Correct ANSWER is (b) False

The best I can explain: The COEFFICIENT of effectiveness increases with the relative size of the LARGER opening. It DEPENDS on the direction of the wind relative to the opening.

Correct option is (d) 100%

For explanation: RELATIVE humidity is the ratio of the amount of water VAPOUR present in the air to the amount of vapour if the air were SATURATED, provided the temperature remains the same. HENCE, relative humidity of saturated air is 100%.

Correct CHOICE is (B) MECHANICAL

The BEST I can explain: The mechanical system is costly, but it results in a considerable INCREASE in the efficiency of the person under the command of the system. This system is adopted for big offices, banks, industrial plants, theatres, etc.

The correct choice is (b) 1 to 1000000

For explanation I would SAY: But this wide range is covered on logarithmic SCALE between 1 to 130 db units. One db unit is approximately the smallest CHANGE of sound intensity which the human ear is able to appreciate.

Correct OPTION is (c) Hertz

For explanation: The range of HUMAN ear is very WIDE extending from 20 Hz to 20000 Hz. It may be NOTED that the range from the lowest to the highest note of the PIANO is about 27.5 Hz to 4186 Hz.

The correct CHOICE is (b) False

Explanation: Intensity of sound is INDEPENDENT of the ear of the listener. HOWEVER, LOUDNESS does depend on the ear of the listener. There is a possibility that the same listener GIVES different judgments about the loudness of sounds having the same intensity but different frequencies.

The correct choice is (c) Cool

Easiest explanation: The cooling can be carried out by MECHANICAL refrigeration or water spray or by cold water. In mechanical refrigeration system, volatile refrigerant is COMPRESSED, COOLED and allowed to EXPAND and then, it is passed through coils. Such coils absorb heat from the incoming air.

Right choice is (B) Area

The BEST EXPLANATION: The absorption of a SURFACE is the product of the area of the surface and its absorption coefficient. The absorption coefficient is used to indicate the SOUND reducing the effect of an absorber which depends on its area and on the efficiency of the material.

Right option is (a) Air CONDITIONING

For EXPLANATION: Air conditioning is the most effective system of artificial ventilation and as it involves MANY other aspects. It is so as to make the air to suit the physiological requirements of the human body or to the needs of industrial processes.

The correct ANSWER is (c) Areas

Explanation: According to the Indian Standard Code IS: 3362-1977, in the case of natural ventilation, flow per UNIT AREA of the opening is greatest when the inlet and outlet openings are of nearly equal areas. ALSO, inlet openings should be LOCATED on the windward side and outlet openings should be located on the leeward side.

Right option is (B) False

The BEST EXPLANATION: The auditorium rear WALL should not be concave in shape. It should be either flat or convex in shape.

The correct choice is (B) False

To elaborate: Sound foci INVOLVES the concentration of sound waves at CERTAIN spots creating high sound intensity. Dead spots are the points where there is a deficiency of the reflected sound waves. HENCE, sound intensity is high at sound foci and LOW at dead spots.

The CORRECT answer is (c) Total absorbing power

To explain I would SAY: In SABINE’s expression for reverberation time t=0.16V/A, A represents total adsorbing power. It is expressed in m^2 sabines. In this expression, V represents the volume of the room in CUBIC metres.

Correct choice is (a) True

Best explanation: The rate of VENTILATION depends on both WIND effect and the stack effect. In ventilation due to wind effect, the rate depends on the direction and VELOCITY of the wind outside. In ventilation due to the stack effect, the rate is affected by the CONVECTION EFFECTS.

Right choice is (a) Stack

Explanation: Ventilation arising from the TEMPERATURE difference between outside and inside takes place DUE to the stack effect. When the temperature of the inside air is higher than the outside air, warmer air passes through the opening situated in the upper part of the room while the cooler air enters the room via the LOWER openings.

Right option is (B) Humidification

Explanation: For humidification, the income air is allowed to pass through pans of water or WETTED cloth strips. For HUMIDIFYING a HUGE quantity of air, the spray humidifiers may be employed.

Right ANSWER is (c) Adsorbent

For explanation I would SAY: The commonly used Adsorbents are SILICA GEL and activated Alumina. When sufficient amount of moisture is collected on absorbents, they can be reactivated by HEATING.

Right ANSWER is (c) Effective TEMPERATURE

Easy explanation: The POPULAR values of effective temperature in winter and summer or 20°C and 22°C respectively. It should however be remembered that the effective temperature indicates same feeling of cool or WARMTH. But it results in HUMAN comfort only when it is correlated with humidity and air movements.

Correct answer is (c) Intensity

Easy explanation: The DIFFERENCE between the two TERMS intensity of SOUND and loudness should also be noted. The intensity of sound is purely a physical quantity that can be accurately measured and it is INDEPENDENT of ear of listener.