Theodore maiman demonstrated the first working laser in 1960. at that time, scientists didn't really know what they were going to use the lasers for, but since then, there have been many new products developed that rely on laser technology. in which of the following products are lasers used? i. cd players ii. barcode scanners iii. hair removal iv. medical surgery

i, ii, iii and iv

Explanation:

Lasers are optical devices used to produce beam of light by the stimulated emission of radiation. As a matter of fact, Laser is the short form for "Light amplification by stimulated emission of radiation". Lasers can be used in various applications such as;

i. laser printers

ii. fiber optic and free-space optical communication

iii. medical surgery and

iv. treatments of skin

v. barcode scanners

vi. hair removal from face, leg, arm and other areas

vii. optical disk drives e.g in CD players

d

explanation:

v=uf/(u-f)

= 5.10/(5-10) convex lens has positive focal length

=50/-5

=-10 cm (formed at other side)

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂