# Physics Essay Example

• Category:
Physics
• Document type:
Assignment
• Level:
High School
• Page:
2
• Words:
804

20 February 2021

Section B

Question 1

Antennas are oriented in a particular plane to best receive the signal from the transmitting plane that emits a radio wave since in such orientation, it ensures that both the receiving and transmission antennas have a maximum directive gain of each other [ CITATION RDe03 l 2057 ].

Question 2

Laser Airborne Depth Sounder (LADS) is a device used to measure accurately the depth of both sea and fresh water. Basically, LADS functions by measuring the time difference that occurs on emission and reception of wave pulses which are reflected from the bottom of the water body as well as water surface [ CITATION Pat12 l 2057 ]. Since the speed of the emitted wave is known, the depth is calculated using the formula below The procedure of measuring the depth of the sea water is as described below

1. A plane directs a beam of laser (from an infra-red laser) light onto the water body

2. The emitted light is then reflected from the water body onto the plane.

3. To produce a beam of green visible light, an electronic device attached to the plane doubles the frequency of the laser light.

4. Infrared light is reflected from the surface of the water body, green light passes through the sea surface and is reflected by the sea bottom. This is as shown in fig. 1 below     Infrared Fig. 1. Measuring of depth of a sea.

The time delay that occurs between a pulse of the infrared and green light being measured in combination with equation 1 above are used to determine the sea depth.

Question 3

1. Light source must be coherent for the waves to superimpose.

2. The intensity of light at P is very high i.e. the point is very Bright. This is because at the point, constructive interference occurs resulting into superposition of the two light waves.

3. assuming it’s a first order, = 1. The wavelength of the light used was calculated as below  The wavelength used is Question 4

Slit Spacing = 1/7000=1.429*10-4 cm The wavelength is Question 5 Also, thus in this case  Thus the maximum number of orders possible is 1

Question 6

The construction of a compact disk is such that it consists of sets of irregularities known as pits and lands. The occurrence of this pits and lands is in a sequence that corresponds to the data that is on the compact disk. A compact Disk player is composed of a laser that has the ability to scan over the track of the compact disk and read the pits and lands. The scanner reads this by detecting phase difference that occurs between the reflected beams. Using the phase difference, the scanner is able to distinguish between pits and lands, and as a result, Binary data is generated.

Question 7

1. The incident light source on striking the photoelectric cell, electrons are emitted. Since the electrons have sufficient energy and the variable voltage supply is set to zero, they overcome the resistance and flow through the circuit. The variable resistor is then adjusted such that enough current is produced that counteract the flow of the electrons. This is done until there is no current flowing through the current, i.e. the ammeter reading is zero. At this point when there is no current flow, the value of the variable voltage supply is the stopping potential. Given by the equation; Thus a plot of stopping voltage against frequency shows relationship.

1. Light of enough frequency on striking a metal surface, there is production of electrons.

Flow of electrons results into production of current.

1. Light waves is composed of photons. This photons have energy. When the photons with sufficient energy strikes a metal surface, energy is transferred from the photons to the electrons on the metal surface. The electrons on gaining sufficient energy, are ejected from the surface and, since they are negatively charged, are attracted towards a positively charged electrons. As they move, current flow is generated.

Question 8

Energy of the photon is given by 1. In this case, the plank’s Constant is 6.626 × 10-34 Js, Speed of the light is 3 × 108 m/s and wavelength of the photon is 600 Nano meters

Thus the photon Energy is; 1. The kinetic Energy of the most energetic photon Thus the kinetic Energy of the most energetic photon is 0.372eV

1. The stopping Voltage

Stopping Voltage is give as Question 9

Converting 30keV to joules From the equation it implies that  Thus the frequency is Question 10  1. This Implies that  1. Electron Microscope utilizes beam of electrons that in magnifying objects and this gives it a high resolution unlike light microscope.

## Bibliography

Carbonneau, Patrice. Fluvial Remote Sensing for Science and Management. John Wiley & Sons, 2012.

Straw, R. Dean. The ARRL antenna book: The Ultimate Reference for Amateur Radio Antennas. ARRL, 2003.