TRUE or FALSE: Most Electromagnetic waves are blocked by the atmosphere.
True
False

If angle "a" is 25°, angle "b" is: a) equal to angle c b) less than angle c c) greater than angle c

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?

Consider a 1000 w iron whose base plate is made of 0.5 cm thick aluminum alloy 2024-t6 (ρ = 2770 kg/m3 and cp = 875 j/kg°c). the base plate has a surface area of 0.03 m2. initially, the iron is in thermal equilibrium with the ambient air at 22°c. assuming 90% of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 200°c.