IOCL Junior Operator Solved Questions & Answers || IOCL Junior Operator General Science Questions and Answers

• The controlling force in spring control is due to torsion of the springs.
• Spring control uses the mechanical properties of springs to generate the controlling force.
• When the moving system deflects, the springs are twisted (experiencing torsion), and their restoring force opposes the deflection, bringing the pointer to a stable position

• An advantage of spring-controlled instruments over gravity-controlled instruments is they can be used in any orientation.
• Spring-controlled instruments can operate in any position (vertical or horizontal) because their controlling force doesn’t rely on gravity

• The control springs also serve the purpose of Carrying current to and from the moving coil.
• Besides providing the controlling torque, the control springs in an indicating instrument also act as electrical connections to carry current to and from the moving coil.
• This dual functionality makes them a crucial component in the instrument’s operation.

• In a spring-controlled instrument, zero adjustment is achieved by adjusting the tension of one spring.
• Zero adjustment in spring-controlled instruments involves mechanically adjusting the spring tension.
• Adjusting the spring tension ensures the instrument’s pointer indicates zero when the input quantity is zero

• Resistances that measure 1 Ω or less are categorized as low resistances.
• Examples of where you might find low resistances include armatures, the series winding of large machines,  and electrical contacts.

• Medium resistances are generally defined as those ranging from 1 Ω to 100 kΩ (which is equal to 100,000 ohms).
• The example of medium resistance are:- Heater resistance, shunt field resistance, relay coil resistance etc

• Any resistance above 100,000 ohms falls into the category of high resistances.
• Objects made of electrical insulators have very high resistance
• Resistances are generally classified into three ranges: low, medium, and high.
• Low resistances are typically those at or below 1 ohm. Medium resistances range from 1 ohm to 100,000 ohms.

• A Megger, also known as a megohmmeter, is specifically designed to measure high electrical and insulation resistance.
• It works by applying a high voltage to the circuit and measuring the resulting current to determine the resistance, often in the megohm range

Instruments typically used for measuring medium resistances includes Kelvin’s bridge, Wheatstone bridge, Slide wire bridge, ohmmeter and Post Office box .

• Wheatstone bridge: The Wheatstone bridge is a very important device used in the measurement of medium resistances. It is considered the most accurate method for measuring resistances.
• Kelvin’s bridge: While primarily known for measuring low resistances, the Kelvin bridge can also be adapted for some medium resistance measurements.
• Ohmmeter: Ohmmeters are electrical instruments used to measure electrical resistance, and can be used to measure medium resistances. The ammeter-voltmeter method is also suitable for measuring medium resistances.

• Single-phase induction-type energy meters are extensively used for measuring electrical energy in AC circuits in homes and industries.
• These meters operate based on the principle of electromagnetic induction.
• The meter’s operation relies on two alternating magnetic fields produced by two coils that induce current in a disc, creating torque and rotating it.