### Exercise 2

Question 11 :

Compact discs, (according to the original CD specifications) hold how many minutes of music?

A). 74 mins
B). 56 mins
C). 60 mins
D). 90 mins
Answer : Option A

Explanation :

According to many stories surrounding the origin of the compact disc, 74 minutes was settled on because it would comfortably contain all of Beethoven's 9th symphony on one disc. Although some stories reference a specific Sony higher-up who claimed this as his favorite piece of music, stories differ. All that's known for sure is that Sony insisted on this and won out over Phillips' original 60 minute proposal.

Question 12 :

Once the active medium is excited, the first photons of light are produced by which physical process?

A). Blackbody radiation
B). Spontaneous emission
C). Synchrotron radiation
D). Planck's oscillation
Answer : Option B

Explanation :

Spontaneous emission is what you see with most "glow in the dark" toys. You excite the toy by exposing it to bright light, then the toy glows in the dark by spontaneously emitting photons as the excited atoms relax back down to their normal state.

Question 13 :

'DTP' computer abbreviation usually means ?

A). Digital Transmission Protocol
B). DeskTop Publishing
C). Data Type Programming
D). Document Type Processing
Answer : Option B

Question 14 :

The average power (in watts) used by a 20 to 25 inch home color television is...?

A). 70-100
B). 25-50
C). 500-800
D). Over 1000
Answer : Option A

Explanation :

About the same as as the most popular light bulb size.

Question 15 :

What does AC and DC stand for in the electrical field?

A). Alternating Current and Direct Current
B). A Rock Band from Australia
C). Average Current and Discharged Capacitor
D). Atlantic City and District of Columbia
Answer : Option A

Explanation :

Electricity is voltage and current. Voltage is electrical pressure, and current is the flow of charged particles. The difference between alternating current (AC) and direct current (DC) is that the electrons in an AC circuit regularly reverse their direction. In a DC circuit electrons always flow in the same direction.