SDI Divemaster Questions and Answers Verified 100% Correct

SDI Divemaster Questions and Answers Verified 100% Correct Diffraction - ANSWER -The random scattering, or divergence, of light rays when they are obstructed by an obstacle. Color Loss Order in Water - ANSWER -ROY G BIV Sound - ANSWER -A series of vibrating waves of energy transmitted through a solid, liquid, or gas. These vibrations are gathered by the ear and transformed into neural signals, which then are interpreted by the brain Speed of Sound in Water - ANSWER -4 times faster than in air Heat - ANSWER -A form of radiant energy that can move through solids, liquids, and gases. Thermal Conductivity Factor of Water - ANSWER -6.0 Thermal Conductivity Factor for Air - ANSWER -0.025 Thermal Conductivity of Water Compared to Air - ANSWER -Heat will be dissipated 25 times faster Archimedes' Principle - ANSWER -The buoyant force on an object is equal to the weight of the fluid displaced by the object. Positively Buoyant - ANSWER -A description of an object whose buoyancy is greater than its weight. The object will float. The mass of water displaced the mass of the object. Negatively Buoyant - ANSWER -A description of an object whose buoyancy is less than its weight. The object will be sinking or sunken. The mass of water displaced the mass of the object. Neutrally Buoyant - ANSWER -A description of an object whose buoyancy is the same as its weight. The object will neither float nor sink. The mass of water displaced = the mass of the object. Lead Weights Buoyancy Compensator Device (BCD) Lung Volume - ANSWER -Items that control diver buoyancy Weight of Seawater - ANSWER -1.03kg/L or 64lb/ft3 Weight of Freshwater - ANSWER -1.00kg/L or 62.4/ft3 Buoyancy Equation - ANSWER -=Weight of Object - (Liters displaced x kg per liter of water) =Weight of Object - (ft3 displaced x lbs per ft3 of water) Negative Buoyancy Equation - ANSWER -Liters required = (kg of negative buoyancy) / (kg per liter of water) ft3 required = (lbs of negative buoyancy) / (lbs per ft3 of water) Pressure - ANSWER -The force or weight pressing upon a surface. Barometer - ANSWER -An instrument that measures atmospheric pressure. Ambient Pressure - ANSWER -Also known as absolute pressure, this refers to the total force being exerted simultaneously by all existing sources of pressure. Atmospheric Pressure - ANSWER -One barometric unit of measure (1 bar or 1kg/cm2) One atmospheric unit of measure (1 atm or 14.7lbs/in2) 1 bar = 1 atm Pressure increase by 1 bar or 1 atm - ANSWER -Every 10m or 33ft of seawater Gauge Pressure - ANSWER -The manner in which a diver's instruments measure and display pressure-related information. It disregards atmospheric pressure and only provides a measurement of the actual force being exerted by another source of pressure. Bar Conversion - ANSWER -= psi / 14.7 Psi Conversion - ANSWER -= bar x 14.7 Meters Conversion - ANSWER -= feet / 3.3 Feet Conversion - ANSWER -= meters x 3.3 Depth to Pressure Calculation (Seawater) - ANSWER -= (meters / 10) + 1 = (meters + 10) / 10 = (feet / 33) + 1 = (feet + 33) / 33 Pressure to Depth Calculation (Seawater) - ANSWER -= (bar - 1) x 10 = (bar x 10) - 10 = (atm - 1) x 33 = (atm x 33) - 33 Depth to Pressure Calculation (Freshwater) - ANSWER -= (meters / 10.3) + 1 = (meters + 10.3) / 10.3 = (feet /34) + 1 = (feet + 34) / 34 Pressure to Depth Calculation (Freshwater) - ANSWER -= (bar - 1) x 10.3 = (bar x 10.3) - 10.3 = (atm - 1) x 34 = (atm x 34) - 34 Seawater to Freshwater - ANSWER -= msw x 1.03 = fsw x 1.03 Freshwater to Seawater - ANSWER -= mfw / 1.03 = ffw / 1.03 Boyle's Law - ANSWER -Any change in pressure applied upon a fixed amount of gas at a constant temperature will result in a corresponding and inversely proportional change in the volume of that gas. P1V1 = P2V2 Effects of Boyle's Law - ANSWER -- Lungs (Breathe continuously) -Middle Ears and Nasal Sinuses (Clear ears) -Mask Squeeze Air in the BCD/Dry Suit - ANSWER -To maintain proper buoyancy control the diver needs to add air during descent and vent air during ascent.