Higher Physics Homework – Lasers and Irradiance answers
a/ The excited electrons are stimulated by a photon to a lower energy
level and emit a photon of exactly the same energy. The two photons are
in phase, travel in the same direction and are of the same frequency.
They therefore amplify. This continues throughout the lasers medium in
a chain reaction if enough atoms are excited (population inversion)
b/ I = P/A
P =IxA
= 4 x 105 x 1.25 x 10-5
= 5W
E = Pxt
= 5 x 100
= 500J
c/
P=IxA
x (¶ x r2)
= 8 x 10-4 W
ii/ The radius of the spot is of comparable size as the beam is
parallel. It does not follow the inverse square law that other
radiations follow.
= 1020
Higher Physics Homework – Lasers and Irradiance answers
a/ The excited electrons are stimulated by a photon to a lower energy
level and emit a photon of exactly the same energy. The two photons are
in phase, travel in the same direction and are of the same frequency They
therefore amplify. This continues throughout the lasers medium in a
chain reaction if enough atoms are excited (population inversion)
b/ I = P/A
P =IxA
= 4 x 105 x 1.25 x 10-5
= 5W
E = Pxt
= 5 x 100
= 500J
c/
P=IxA
x (¶ x r2)
= 8 x 10-4 W
ii/ The radius of the spot is of comparable size as the beam is
parallel. It does not follow the inverse square law that other
radiations follow.
= 1020
Higher Physics Homework – Lasers and Irradiance answers
a/ The excited electrons are stimulated by a photon to a lower energy
level and emit a photon of exactly the same energy. The two photons are
in phase, travel in the same direction and are of the same frequency.
They therefore amplify. This continues throughout the lasers medium in
a chain reaction if enough atoms are excited (population inversion)
b/ I = P/A
P =IxA
= 4 x 105 x 1.25 x 10-5
= 5W
E = Pxt
= 5 x 100
= 500J
c/
P=IxA
x (¶ x r2)
= 8 x 10-4 W
ii/ The radius of the spot is of comparable size as the beam is
parallel. It does not follow the inverse square law that other
radiations follow.
= 1020
Higher Physics Homework – Lasers and Irradiance answers
a/ The excited electrons are stimulated by a photon to a lower energy
level and emit a photon of exactly the same energy. The two photons are
in phase, travel in the same direction and are of the same frequency They
therefore amplify. This continues throughout the lasers medium in a
chain reaction if enough atoms are excited (population inversion)
b/ I = P/A
P =IxA
= 4 x 105 x 1.25 x 10-5
= 5W
E = Pxt
= 5 x 100
= 500J
c/
P=IxA
x (¶ x r2)
= 8 x 10-4 W
ii/ The radius of the spot is of comparable size as the beam is
parallel. It does not follow the inverse square law that other
radiations follow.
= 1020