Q1. A line drawn on a chart which joins all points where the value of magnetic variation is zero is called an:
Correct answer is – agonic line
Q2. A line running through positions where the magnetic and the true meridians are parallel, is called
Correct answer is – An agonic line
Q3. A negative (westerly) magnetic variation signifies that :
Correct answer is – True North is East of Magnetic North
Q4. A simple magnet is surrounded by a magnetic field having the following properties:
Correct answer is – The field’s direction is from the magnets red pole to the magnets blue pole
Q5. An Agonic line is a line that connects:
positions that have zero variation (
- Definition: A-Gonic = No Angle = Zero Variation.
)
Q6. An isogonal
Correct answer is – Is a line running through all positions having the same variation
Q7. As you move from a lower to a higher southern magnetic latitude, the characteristics of the terrestrial magnetic field will change:
Correct answer is – The inclination will increase and the vertical component of the field will increase
Q8. At a specific location, the value of magnetic variation:
varies slowly over time (
- Definition: Variation is determined by the physical location of the Earth’s magnetic poles.
- Secular Change: The poles migrate slowly over time (secular movement), causing variation values at any specific location to drift annually.
)
Q9. Complete the following statement regarding magnetic variation. The charted values of magnetic variation on earth normally change annually due to:
Correct answer is – magnetic pole movement causing numerical values at all locations to increase or decrease
Q10. Consider the following statements on magnetic variation:
Correct answer is – The variation is east when True North seems to be located west of Magnetic North
Q11. Grivation is the combination of
Variation and Grid Convergence (
- Formula: Grivation (Grid Variation) = Grid Convergence + Magnetic Variation.
)
Q12. In a particular position the horizontal and the total strength of the terrestrial magnetic field are the same. This position is
Correct answer is – At the magnetic equator
Q13. In a particular position the total strength of the terrestrial magnetic field is 5 nanotesla. The inclination is 55°. What is the strength of the horizontal component in this position?
Correct answer is – 2.87 nanotesla
- Using the values provided:
- Total Force (T): 5 nanotesla
- Angle of Dip (Inclination): 55°
- Now, apply these values to the formula:
- H = T × cos(Angle of Dip)
- H = 5 × cos(55°)
- H = 5 × 0.573576
- H ≈ 2.868 nanotesla
Therefore, the strength of the horizontal component in this position is approximately 2.87 nanotesla.
Q14. Isogonals are lines of equal :
Correct answer is – magnetic variation.
Q15. Isogonals converge at the:
Correct answer is – North and South geographic and magnetic poles
Q16. Isogonic lines connect positions that have:
Correct answer is – the same variation
Q17. Isogrives are lines that connect positions that have:
the same grivation (
- Definition: Iso (Equal) + Grive (Grid Variation).
)
Q18. Magnetic dip angle at the south pole is?
90 degrees. (
- Poles: Flux lines are vertical.
- Angle: Vertical = 90 degrees.
)
Q19. Magnetic heading can be found from true heading using?
A compass and a map showing isogonal lines. (
- Formula: Magnetic = True +/- Variation.
- Source: Variation is found on charts using Isogonal lines (lines of equal variation).
)
Q20. Permanent magnetism in aircraft is caused by?
The hammering of rivets during construction. (
- Process: Percussion (hammering) while sitting in the Earth’s magnetic field aligns the magnetic domains in the steel.
- Result: This creates “Sub-permanent” or Hard Iron magnetism that persists.
)
Q21. The angle between True North and Magnetic North is called :
Correct answer is – variation
Q22. The angular difference between the geographical meridian and the magnetic meridian running through the same position is named
Correct answer is – Variation
Q23. The approximate location of the Magnetic North Pole is
Correct answer is – 7300N 10000W
Q24. The compass needle marked red
Correct answer is – Is called “The North-seeking Pole”
Q25. The dip angle in the terrestrial magnetic field is given by the following equation:
Correct answer is – Dip = cos-1 (H/T)
Q26. The directive force of the earth’s magnetic field:
is greatest at the magnetic equator (
- Definition: Directive Force = Horizontal Component (H).
- Max Value: H is maximum where Dip is zero (Equator) because H = T cos(0) = T.
)
Q27. The Earth can be considered as being a magnet with the:
Correct answer is – blue pole near the north pole of the earth and the direction of the magnetic force pointing straight down to the earth’s surface
Q28. The horizontal component of the earth’s magnetic field:
Correct answer is – is approximately the same at magnetic latitudes 50°N and 50°S
Q29. The lines on the earth’s surface that join points of equal magnetic variation are called:
Correct answer is – isogonals
Q30. The magnetic moment of a magnet:
is the product of pole strength and effective length (
- Physics Definition: M = m times l (Pole Strength times Length between poles).
)
Q31. The north and south magnetic poles are the only positions on the earth’s surface where:
Correct answer is – a freely suspended compass needle will stand vertical
Q32. The red pole of a freely suspended magnet will point towards ……. and at latitude 60N will point ……. at an angle known as the angle of
the North magnetic pole, downwards, dip (
- Convention: Red Pole = North Seeking Pole. Points North.
- Dip: In Northern Hemisphere, the field lines dive into the Earth. The North pole of the magnet points Downwards (Dip).
)
Q33. The sensitivity of a direct reading compass varies:
Correct answer is – directly with the horizontal component of the earth’s magnetic field
Q34. The slow change in the earth’s magnetic variation is known as the ……. change and is caused by
secular, westerly movement of the magnetic pole (
- Terminology: Long-term magnetic change is called Secular change.
- Trend: Historical data indicates a general westerly drift of the magnetic field patterns.
)
Q35. The total Magnetic Force of the terrestrial magnetic field
Correct answer is – Is strongest at the magnetic poles
Q36. The value of magnetic variation:
has a maximum of 180^{circ} (
- Geometry: Variation is the angle between True North and Magnetic North.
- Limit: Just like longitude, the angular difference between two meridians can reach a maximum of 180 degrees (at positions between the poles).
)
Q37. What is the value of the magnetic dip at the magnetic south pole ?
Correct answer is – 90°
Q38. When is the magnetic compass most effective?
Correct answer is – About midway between the magnetic poles
Q39. Where is a compass most effective?
About midway between the Magnetic Pole (
- Effectiveness: Depends on Directive Force (H).
- Location: Max H is at Magnetic Equator. “Midway between Magnetic Poles” describes the Magnetic Equator region.
)
Q40. Which of the following materials are classed as ferromagnetic:
iron, cobalt steel, chromium steel (
- Ferromagnetic: Materials strongly attracted to magnets.
- List: Iron, Cobalt, Nickel, and their alloys (Steel). Copper and Carbon-fibre are not ferromagnetic.
)
Q41. Which of the following statements concerning earth magnetism is completely correct?
An isogonal is a line which connects places with the same magnetic variation, the Aclinic is the line of zero magnetic dip (
- Isogonal: Equal Variation.
- Aclinic: Zero Dip (Magnetic Equator).
- Matching: Option 2 combines these definitions correctly.
)
Q42. Which of the following statements concerning the earth’s magnetic field is completely correct?
Correct answer is – The blue pole of the earth’s magnetic field is situated in North Canada
Q43. Which of these is a correct statement about the Earth’s magnetic field?
It acts as though there is a large blue magnetic pole in Northern Canada (
- Polarity Convention: The North-Seeking (Red) pole of a magnet points North. Therefore, the Earth’s Geometric North must contain a Blue (South) magnetic polarity to attract it.
)