The area of a telescope lens is 6.679 × 103 mm2. (a) what is the area in square feet (ft2)? enter your answer in scientific notation. (b) if it takes a technician 43.4 s to polish 1.46 × 102 mm2, how long does it take her to polish the entire lens?

Given:

Area of a telescope lens = 6.679 *

a)

Area of lens = 6.679 * * 1.076*10^{-5} ft^{2}[/tex]

                     = 7.187 *

b) Time taken to polish an area of 1.46 * = 43.4 s

Therefore, time taken to polish the entire lens

                   = 43.4 * 6.679 *

                   = 1985 sec  

pure water does not conduct electricity very well. however, when certain substances are dissolved in water, the solution does conduct electricity. you can make a simple device that shows how well a solution conducts electricity. this device uses a flashlight bulb to indicate how well the solution conducts electricity. the better the solution conducts electricity, the brighter the bulb will glow.

explanation:

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.