SSB Questions Related To Defence

Personal Interview in a SSB is the most important factor in the selection of a candidate. PI cannot be predicted and the IO can ask you questions from any field. When it comes to the technical portion then these questions are very basic in nature and somehow they are related to defence and science. IO never goes in much deeper detail, but if you say that it is your childhood dream then IO will ask you anything. 

Some of these frequent asked questions at SSB are:

• Rotor blades have an airfoil shape, like the wings of an aircraft. So as the rotor turns, the air flows more over the top of the blades than does it below. This creates enough lift for flights.
• Second rotor rotates vertically or nearly vertically. The tail rotor’s position and distance from the center of gravity allow it to develop thrust in an opposite direction of the main rotor’s rotation to counter the torque effect created by main rotor. It prevents the chopper from spinning out of control. If it is not present, then the chopper will spin on its axis.
  

• RADAR stands of Radio Detection and Ranging. It is a system which uses radio-waves to determine the range, altitude, direction or sped of objects. It can be used to detect aircrafts, ships, missiles, vehicles, weather formations and terrain as well.
• Transmitter emits radio waves called radio signals in predetermined directions. When these come into contact with an object they are usually reflected or scattered in many directions and these signals are reflected back towards the transmitter which makes the radar work. Time difference between transmission of signal and reception of signals helps to calculate the distance.

• SONAR stands for Sound navigation and ranging It is system that uses sound propagation to navigate, communicate and detect objects on or under the surface of water. Ultrasonic waves are transmitted through water. When these waves come in contact with any object then these are reflected by the object in the water which produces an echo signal. By noting the time interval between the generation of the pulse and reception of the echo-signal, the distance of the object can be easily calculated.

Difference between Sound Waves and Radio Waves

• SONAR uses sound waves whereas the RADAR uses radio waves
• Sound waves can be heard because of high frequency but we need electronic devices to hear or see the radio waves.
• Radio waves travel greater distance because of longer wavelength.
• Sound waves cannot travel in vacuum because there is no air foe the waves to oscillate in. Whereas the radio waves can travel through vacuum. 

• AEWCS stands for Airborne Earning Warning and Control System. It is a system designed to detect aircrafts, ships and vehicles at long ranges. AEWCS is used at high altitude; the radars on the aircraft allow distinguishing between friendly and hostile objects hundreds of miles away. It carries surveillance and performs command and control of air battle space by directing fighter and attack aircrafts strikes. AEWCS and AWACS are the same. AWACS stands for Airborne Warning And Control System. 

• Cartridges have the gun powder, projectile and a mechanism to ignite gunpowder packed into one unit. When the gun’s trigger is pulled then it strikes the primer which catches fire which ignites the gunpowder and the projectile is forced out of the shell because of expanding gases. 

• Ballistic missiles are big, heavy and expensive. It has warheads on the rocket. Ballistic missiles reach heights beyond the atmosphere and re-enter atmosphere & deliver warheads to predetermined multiple targets. Its detection is easy.
• Cruise missiles are small, light but less powerful. These missiles do not go in the atmosphere but rather it stays very close to ground to prevent detection and hit the selected targets. Cruise missiles are difficult to detect as compared to ballistic missiles. 

• A rifle has a long barrel and has grooves inside the barrel which in result produces spin of a bullet which counters the effect of wind. Rifles are heavy and are more accurate of long barrel length and spin produced. Bullet shots from rifle travel faster.
• Carbines have small barrel length without any grooves. These are lighter than assault rifles but these are not so accurate and bullet shots travel slower than the rifle. The carbines are made from the rifles. 

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