Which of the following statements with reference to Coriolis force is/are correct? 1. Coriolis force acts perpendicular to the pressure gradient force. 2. At the equator, the Coriolis force is zero and the wind blows perpendicular to the isobars.
- (a)1 only
- (b)2 only
- (c)Both 1 and 2
- (d)Neither 1 nor 2
Correct — C, Both 1 and 2. The Coriolis force always acts at right angles to the direction of motion, and since the pressure-gradient force sets the wind's initial direction, the Coriolis force ends up perpendicular to the pressure-gradient force — so Statement 1 holds. The force also varies with the sine of the latitude, which is zero at the Equator; with no deflection there, the wind blows straight down the pressure gradient, crossing the isobars at right angles — so Statement 2 holds too.
- (a)1 only — Statement 2 is also a correct textbook fact: the Coriolis force is zero at the Equator and the wind there blows perpendicular to the isobars, so choosing 1 alone leaves out a true statement.
- (b)2 only — Statement 1 is correct as well — the Coriolis force acts perpendicular to the pressure-gradient force — so restricting the answer to 2 drops a true statement.
- (d)Neither 1 nor 2 — Both statements are accurate descriptions of the Coriolis force, so rejecting both is wrong.
The Coriolis force is an apparent deflecting force caused by the Earth's rotation. It acts perpendicular to the direction of air movement — to the right in the Northern Hemisphere and to the left in the Southern — and its strength depends on the sine of the latitude, making it zero at the Equator and greatest at the poles.
Winds start out blowing from high to low pressure along the pressure gradient. The Coriolis force turns that flow sideways, so it sits at right angles to the pressure-gradient force. Where the Coriolis force disappears (at the Equator), nothing bends the wind and it runs straight across the isobars — exactly what both statements say.
- The Coriolis force is produced by the Earth's rotation and deflects moving air.
- It acts perpendicular to the pressure-gradient force that drives the wind.
- Its magnitude grows with the sine of the latitude — zero at the Equator, maximum at the poles.
- Away from the Equator, the balance of the Coriolis and pressure-gradient forces gives winds that blow nearly parallel to the isobars (geostrophic wind).
Both printed statements are correct, so the answer is Both 1 and 2.
- The Coriolis force is perpendicular to the wind's motion, so it does no work and only changes direction.
- It is zero at the Equator and maximum at the poles — the reverse of the pressure-gradient effect on wind speed.
Coriolis force is tested as a two-statement true/false set pairing its right-angle action with its zero value at the Equator.
With reference to “Coriolis force”, which of the following statements is/are correct? 1. It increases with increase in wind velocity. 2. It is maximum at the poles and is absent at the equator. Select the answer using the code given below.
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer(c) Both 1 and 2
The same Coriolis force. UPSC tests its dependence on wind speed and latitude (zero at the equator, maximum at the poles); the NDA item tests the companion facts that it acts at right angles to the pressure-gradient force and vanishes at the equator so winds cross the isobars.
Where is the Coriolis Effect the largest?
- (a) At the Equator
- (b) At the Tropic of Capricorn and Tropic of Cancer
- (c) At the North Pole
- (d) At 45 degree latitude in each hemisphere
Answer(c) At the North Pole
The same Coriolis force from the latitude angle. This earlier NDA item fixes where it is strongest (the poles, where sin of the latitude equals 1); the 2025 question uses the flip side — it is zero at the equator, so winds there blow straight across the isobars.
- practice — not a real PYQ
The Coriolis force is maximum at which of the following?
- (a)The Equator
- (b)The Tropics
- (c)45° latitude
- (d)The poles
Answer(d) The poles — the force varies with the sine of the latitude, which is largest (equal to 1) at 90°.
- practice — not a real PYQ
In the Northern Hemisphere the Coriolis force deflects winds to their
- (a)left
- (b)right
- (c)front
- (d)rear
Answer(b) right — in the Northern Hemisphere moving air is deflected to the right of its direction of motion.