Quick Answer: Pencil Jockey Apparatus is a handheld contact probe with a Bakelite-moulded handle and brass-plated contact, used to find balance points on meter bridge, Wheatstone bridge and potentiometer wires.
Last updated: October 2026
Key Features
Bakelite-moulded insulated handle
Brass-plated contact for temporary contact with the resistance wire
Locating notch for placing the contact over the wire
Pencil-style format for controlled movement along the wire
Momentary contact, so readings can be checked without constant pressure
Supplied as a single accessory
Technical Specifications
Specification
Value
Product type
Handheld electrical contact probe
Primary application
Locating balance or null points on resistance wire
Handle
Bakelite moulded
Contact
Brass-plated
Contact arrangement
Locating notch provided
About This Product
Touching the wire briefly at different points while watching the galvanometer, the user finds the spot where deflection falls to zero and reads the balance length from the scale. The jockey is an accessory rather than a measuring instrument, so in Electrical And Electronics practicals it is paired with a meter bridge or potentiometer to find an unknown resistance, compare cell emf or measure internal resistance.
Frequently Asked Questions
Q1. Why is it called a pencil jockey? Its long insulated handle is held and moved like a pencil while the contact end touches the bridge wire.
Q2. Does the jockey measure resistance directly? No. It only locates the balance position. Resistance is then calculated from the circuit values and the measured balance length.
Q3. Should the jockey be pressed firmly on the wire? No. Use only enough pressure for momentary contact, and do not drag the tip along the wire, as this can scratch or stretch it and affect results.
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