Subtopic: Functional requirements, principles of working, construction and operation of manual, animal, tractor and renewable energy operated equipment for tillage, sowing, planting, fertilizer application, inter-cultivation, spraying, mowing, chaff cutting, harvesting and threshing
Question Statement:
Which of the following statements regarding electrostatic crop sprayers is/are CORRECT?
Options:
(A) Electrostatic charging creates an electrical charge-to-mass ratio ($q/m$) typically between $1.0$ and $5.0\text{ mC/kg}$ on spray droplets
(B) Charged droplets induce an opposite mirror image charge on earthed plant foliage, generating attractive Coulomb forces that wrap droplets onto abaxial (underside) leaf surfaces
(C) Like charges on adjacent droplets cause cloud self-expansion (mutual repulsion), reducing droplet coalescence in transit
(D) Electrostatic sprayers require extremely high liquid application volumes exceeding $500\text{ L/ha}$ to maintain electrode conductivity
Answer Key:
A, B, C
Step-by-Step Solution & Explanation
- **A is correct:** Standard electrostatic induction nozzles achieve $q/m$ levels of $1\text{--}5\text{ mC/kg}$.
- **B is correct:** Induced charge on grounded plant leaves produces the famous 'wrap-around effect', depositing pesticide on hidden undersides of leaves.
- **C is correct:** Mutually repelling like charges prevent agglomeration and maintain fine droplet dispersion.
- **D is incorrect:** Electrostatic sprayers are strictly Ultra-Low Volume (ULV) or Low Volume (LV) systems operating typically at $20\text{--}60\text{ L/ha}$.