Influence of moisture, temperature and sunlight on the severity of air pollution effects on materials.
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The acoustical design of spaces involves the reinforcement of desirable sound and the control of undesirable noise. A room’s acoustic is depending on its shape, form, volume and the nature of its surfaces Room form
-Parallel surfaces reflect sound back and forth across a surface -Parallel surface may cause excessive reverberation and undesirable echoes or flutter
-Concave surfaces-focus sound
-create undesirable hot spot of sound -convex surfaces-diffuse sound
-desirable in listening
-High cubicle and long narrowly proportionated spaces may require splayed surfaces to diffuse reflected sounds and absorbents surfaces to control reverberation.
Nature of the surface
-hard surface reflect sound while soft surface tend to absorb sound energy The level of sound, reverberation time and resonance desire for the intended use of the space will determine the area and disposition of hard and soft surfaces within the space.
Calculate the current flowing in the resistance of a lamp rated at 240 V and 60 W. W = VA
A = W
Current = 60 = 0.25 A
R = V = 240 = 960
Resistance = 960 Ω
Calculate the current flowing in the resistance of a 2 kW immersion heater connected to a 250 V supply. ii)
W = VA
A = W
Current = 2 x 1000
R = V = 250 = 31.35
Resistance = 31.25Ω
Check using formula, W = A2 R
W = 82 x 31.25
W = 2000 or 2 kW
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