INSTRUMENTS AND WIRING

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• Q1: What are Electrical Measuring Instruments?
  Ans: Electrical measuring instruments are devices used to measure electrical quantities such as voltage, current, resistance, power, and energy.
• Q2: Name six Electrical Measuring Instruments.
  Ans: The six electrical measuring instruments are:

  • ➔ Ammeter
  • ➔ Voltmeter
  • ➔ Ohmmeter
  • ➔ Wattmeter
  • ➔ Energy Meter
  • ➔ Multimeter
• Q3: State the classification of Electrical Measuring Instruments.
  Ans: Electrical measuring instruments are classified as:

  • ➔ Absolute Instruments
  • ➔ Secondary Instruments
• Q4: What are Absolute Instruments? Name some.
  Ans: Absolute instruments are those instruments which measure electrical quantity in terms of physical constants without comparison.
  Examples are:

  • ➔ Tangent Galvanometer
  • ➔ Rayleigh Current Balance
• Q5: What are Secondary Instruments? Name some.
  Ans: Secondary instruments are those instruments which give direct reading of the electrical quantity after calibration.
  Examples are:

  • ➔ Ammeter
  • ➔ Voltmeter
  • ➔ Wattmeter
• Q6: State the types of Secondary Instruments according to the mode of working.
  Ans: The types of secondary instruments are:

  • ➔ Indicating Instruments
  • ➔ Recording Instruments
  • ➔ Integrating Instruments
• Q7: What are Analogue Instruments? Name some.
  Ans: Analogue instruments show readings with a pointer moving over a scale.
  Examples are:

  • ➔ Analogue Ammeter
  • ➔ Analogue Voltmeter
  • ➔ Analogue Multimeter
• Q8: What are Digital Instruments? Name some.
  Ans: Digital instruments show readings in numerical (digit) form on a display.
  Examples are:

  • ➔ Digital Voltmeter
  • ➔ Digital Ammeter
  • ➔ Digital Multimeter
• Q9: What is the Parallex error?
  Ans: Parallax error is the error that occurs when the pointer of an instrument is viewed from an angle instead of directly in front, causing incorrect reading.
• Q10: How can we remove the Parallex error?
  Ans: Parallax error can be removed by:

  • ➔ Viewing the scale directly from the front
  • ➔ Using a mirror scale and aligning the pointer with its reflection
• Q11: Define Meter.
  Ans: A meter is an electrical instrument used to measure a specific electrical quantity such as current, voltage, or resistance.
• Q12: Name the types of Meters.
  Ans: The types of meters are:

  • ➔ Ammeter
  • ➔ Voltmeter
  • ➔ Ohmmeter
  • ➔ Energy Meter
• Q13: What is an Ammeter?
  Ans: An ammeter is an instrument used to measure electric current in a circuit. The unit of current is ampere (A).
• Q14: Briefly explain the working principle of an Ammeter.
  Ans: An ammeter works on the principle of magnetic effect of electric current. When current flows through the coil, it produces a magnetic field which causes the pointer to deflect and indicate the current value.
• Q15: State the uses of an Ammeter.
  Ans: Uses of an ammeter are:

  • ➔ To measure current in a circuit
  • ➔ To check electrical faults
  • ➔ To test electrical devices
• Q16: What is a Voltmeter?
  Ans: A voltmeter is an instrument used to measure the voltage or potential difference between two points in a circuit.
• Q17: Briefly explain the working principle of a Voltmeter.
  Ans: A voltmeter works on the principle of Ohm’s law. It measures the voltage by allowing a small current to pass through a high resistance and displays the potential difference.
• Q18: State the uses of a Voltmeter.
  Ans: Uses of a voltmeter are:

  • ➔ To measure voltage in a circuit
  • ➔ To check battery voltage
  • ➔ To test electrical equipment
• Q19: State the difference between an Analogue and a Digital Voltmeter.
  Ans: The differences are:

  • ➔ Analogue voltmeter shows reading with a pointer, while digital voltmeter shows reading in numbers.
  • ➔ Analogue is less accurate, while digital is more accurate.
  • ➔ Analogue has parallax error, while digital has no parallax error.
• Q20: What is an Ohm Meter?
  Ans: An ohm meter is an electrical instrument used to measure the resistance of a circuit or component. The unit of resistance is ohm (Ω).
• Q21: State the types of an Ohm meter.
  Ans: The types of ohm meter are:

  • ➔ Series Type Ohm Meter
  • ➔ Shunt Type Ohm Meter
  • ➔ Multirange Ohm Meter
• Q22: What is a Series Type Ohm meter?
  Ans: A series type ohm meter is an instrument in which the resistance to be measured is connected in series with the meter. It is mainly used to measure high resistance values.
• Q23: What is a Shunt Type Ohm meter?
  Ans: A shunt type ohm meter is an instrument in which the resistance to be measured is connected in parallel (shunt) with the meter. It is mainly used to measure low resistance values.
• Q24: What is a Multirange Ohm meter?
  Ans: A multirange ohm meter is an instrument that can measure resistance over a wide range by selecting different ranges using a switch.
• Q25: State the uses of an Ohm meter.
  Ans: Uses of an ohm meter are:

  • ➔ To measure resistance
  • ➔ To check continuity of a circuit
  • ➔ To detect faults in electrical components
• Q26: What is a Multimeter or an AVO meter?
  Ans: A multimeter (AVO meter) is an instrument used to measure current (Ampere), voltage (Volt), and resistance (Ohm) in a single device.
• Q27: Briefly explain the working principle of a multimeter.
  Ans: A multimeter works on the principle of Ohm’s law. It uses internal circuits and resistors to measure current, voltage, and resistance by switching between different modes.
• Q28: State the uses of a Multimeter.
  Ans: Uses of a multimeter are:

  • ➔ To measure voltage, current, and resistance
  • ➔ To test electrical components
  • ➔ To check continuity and faults in circuits
• Q29: What is a Watt Meter?
  Ans: A watt meter is an electrical instrument used to measure electric power in a circuit. The unit of power is watt (W).
• Q30: What is a Current Coil?
  Ans: A current coil is a coil in a watt meter connected in series with the circuit. It carries the load current and produces a magnetic field.
• Q31: What is a Potential Coil?
  Ans: A potential coil is a coil in a watt meter connected in parallel with the circuit. It measures the voltage and produces a magnetic field proportional to voltage.
• Q32: What is an Energy Meter?
  Ans: An energy meter is an instrument used to measure electrical energy consumed over time. The unit of energy is kilowatt-hour (kWh).
• Q33: What is a Pyrometer?
  Ans: A pyrometer is an instrument used to measure very high temperatures without direct contact, such as in furnaces.
• Q34: What is a Lux meter?
  Ans: A lux meter is an instrument used to measure the intensity of light falling on a surface. The unit of illumination is lux.
• Q35: What is a Techometer?
  Ans: A tachometer is an instrument used to measure the speed of rotation of a machine or motor, usually in revolutions per minute (RPM).
• Q36: Define Wiring.
  Ans: Wiring is the system of connecting electrical devices and distributing electricity through conductors, cables, and accessories in a building.
• Q37: State the types of Wiring System.
  Ans: The types of wiring system are:

  • ➔ Batten Wiring System
  • ➔ Casing Capping Wiring System
  • ➔ PVC Casing Capping Wiring System
  • ➔ PVC Conduit Wiring System
• Q38: What is the Batten Wiring System?
  Ans: Batten wiring system is a method in which insulated wires are fixed on wooden battens using clips.
• Q39: State the uses of Batten Wiring System.
  Ans: Uses of batten wiring system are:

  • ➔ Used in houses for low voltage installations
  • ➔ Used in temporary wiring
  • ➔ Used in small buildings
• Q40: State any four advantages of Batten Wiring System.
  Ans: Advantages of batten wiring system are:

  • ➔ Low cost
  • ➔ Easy to install
  • ➔ Easy to maintain
  • ➔ Simple design
• Q41: State any four disadvantages of Batten Wiring System.
  Ans: Disadvantages of batten wiring system are:

  • ➔ Not suitable for damp places
  • ➔ Poor protection against mechanical damage
  • ➔ Short life
  • ➔ Not suitable for heavy loads
• Q42: What is the Casing Caping Wiring System?
  Ans: Casing capping wiring system is a method in which wires are enclosed in wooden casing and covered with a cap for protection.
• Q43: State the uses of Casing Caping Wiring System.
  Ans: Uses of casing capping wiring system are:

  • ➔ Used in residential buildings
  • ➔ Used where moderate protection is required
  • ➔ Used for indoor wiring
• Q44: State any four advantages of Casing Caping Wiring System.
  Ans: Advantages of casing capping wiring system are:

  • ➔ Good protection of wires
  • ➔ Easy to inspect
  • ➔ Long life
  • ➔ Neat appearance
• Q45: State any four disadvantages of Casing Caping Wiring System.
  Ans: Disadvantages of casing capping wiring system are:

  • ➔ Costly compared to batten wiring
  • ➔ Not suitable for damp places
  • ➔ Can be damaged by insects (wooden casing)
  • ➔ Requires more space
• Q46: What is the PVC Casing Caping Wiring System?
  Ans: PVC casing capping wiring system is similar to wooden casing capping, but it uses PVC (plastic) casing and cap to enclose and protect the wires.
• Q47: State the uses of PVC Casing Caping Wiring System.
  Ans: Uses of PVC casing capping wiring system are:

  • ➔ Used in houses and offices
  • ➔ Used where moisture resistance is needed
  • ➔ Used for indoor wiring
• Q48: State any four advantages of PVC Casing Caping Wiring System.
  Ans: Advantages of PVC casing capping wiring system are:

  • ➔ Moisture resistant
  • ➔ Not affected by insects
  • ➔ Lightweight
  • ➔ Easy installation
• Q49: State any four disadvantages of PVC Casing Caping Wiring System.
  Ans: Disadvantages of PVC casing capping wiring system are:

  • ➔ Can break under high temperature
  • ➔ Less strong than metal conduit
  • ➔ Not suitable for heavy loads
  • ➔ Appearance may degrade over time
• Q50: What is the PVC Conduit Wiring System?
  Ans: PVC conduit wiring system is a method in which electrical wires are drawn through PVC pipes (conduits) to provide strong protection.
• Q51: State the uses of PVC Conduit Wiring System.
  Ans: Uses of PVC conduit wiring system are:

  • ➔ Used in residential and commercial buildings
  • ➔ Used where high protection is required
  • ➔ Used in concealed wiring systems
• Q52: State any four advantages of PVC Conduit Wiring System.
  Ans: Advantages of PVC conduit wiring system are:

  • ➔ High safety
  • ➔ Strong protection against damage
  • ➔ Long life
  • ➔ Suitable for heavy loads
• Q53: State any four disadvantages of PVC Conduit Wiring System.
  Ans: Disadvantages of PVC conduit wiring system are:

  • ➔ High initial cost
  • ➔ Difficult installation
  • ➔ Requires skilled labor
  • ➔ Fault detection is difficult
• Q54: Define Conduit.
  Ans: A conduit is a pipe or tube used to protect and route electrical wires in a wiring system. It is usually made of PVC or metal.
• Q55: State any two advantages of using a conduit.
  Ans: Advantages of using a conduit are:

  • ➔ Provides strong protection to wires
  • ➔ Increases safety by reducing risk of electric shock
• Q56: What is Concealed Wiring?
  Ans: Concealed wiring is a wiring system in which electrical wires are hidden inside walls, ceilings, or floors using conduits.
• Q57: State the advantages of Concealed Wiring.
  Ans: Advantages of concealed wiring are:

  • ➔ Safe from mechanical damage
  • ➔ Better appearance
  • ➔ Long life
  • ➔ Less risk of electric shock
• Q58: State the disadvantages of Concealed Wiring.
  Ans: Disadvantages of concealed wiring are:

  • ➔ High installation cost
  • ➔ Difficult to repair faults
  • ➔ Requires skilled labor
  • ➔ Time-consuming installation
• Q59: What is Open or Surface Wiring?
  Ans: Open or surface wiring is a wiring system in which wires are installed on the surface of walls or ceilings and are visible.
• Q60: State the advantages of Open or Surface Wiring.
  Ans: Advantages of open wiring are:

  • ➔ Low cost
  • ➔ Easy to install
  • ➔ Easy to repair
  • ➔ Suitable for temporary use
• Q61: State the disadvantages of Open or Surface Wiring.
  Ans: Disadvantages of open wiring are:

  • ➔ Poor appearance
  • ➔ Less protection from damage
  • ➔ Short life
  • ➔ Higher risk of electric shock
• Q62: Name any four materials of Cables.
  Ans: Materials of cables are:

  • ➔ Copper
  • ➔ Aluminium
  • ➔ PVC (insulation)
  • ➔ Rubber (insulation)
• Q63: Name some accessories used in Domestic Wiring.
  Ans: Accessories used in domestic wiring are:

  • ➔ Switches
  • ➔ Sockets
  • ➔ Plugs
  • ➔ Fuses
  • ➔ Distribution Board
  • ➔ Circuit Breakers
• Q64: Define Switches. Name the types of Switches
  Ans: A switch is an electrical device used to make or break an electrical circuit.
  Types of switches are:

  • ➔ One Way Switch
  • ➔ Tumbler Switch
  • ➔ Piano Key Switch
  • ➔ Double Pole Switch
• Q65: What is Single or One Way Switch?
  Ans: A single or one way switch is a switch used to control a circuit from one location. It can either turn ON or OFF the circuit.
• Q66: What is a Tumbler Switch?
  Ans: A tumbler switch is a type of switch operated by flipping a lever up or down to open or close the circuit.
• Q67: What is a Piano Key Switch?
  Ans: A piano key switch is a switch operated by pressing a button like piano keys to control the circuit.
• Q68: What is a Bakelite Double Pole Main Switch?
  Ans: A bakelite double pole main switch is a switch made of insulating bakelite material that controls both live and neutral wires of a circuit.
• Q69: What is an Iron Clad Double Pole Main Switch?
  Ans: An iron clad double pole main switch is a heavy-duty switch enclosed in a metal (iron) case, used for controlling both live and neutral wires.
• Q70: What is an Iron Clad Triple Pole Main Switch?
  Ans: An iron clad triple pole main switch is a switch used in three-phase systems to control three live wires simultaneously.
• Q71: What are Lamp Holders?
  Ans: Lamp holders are devices used to hold and connect electric lamps or bulbs safely to the power supply.
• Q72: What is a Batten Holder?
  Ans: A batten holder is a lamp holder fixed directly on a wall or wooden board.
• Q73: What is an Angle Holder?
  Ans: An angle holder is a lamp holder fixed at an angle, usually on a wall, to direct light in a specific direction.
• Q74: What are Pendant Lamp Holders?
  Ans: Pendant lamp holders are holders that hang from the ceiling using a flexible wire or cord.
• Q75: What are Bracket Lamp Holders?
  Ans: Bracket lamp holders are holders mounted on walls using brackets to support the lamp.
• Q76: What is a Push Bar Switch Holder?
  Ans: A push bar switch holder is a lamp holder with a built-in push switch used to turn the lamp ON or OFF.
• Q77: What is a Multi Holder?
  Ans: A multi holder is a device that can hold more than one lamp at the same time.
• Q78: What is an Outlet?
  Ans: An outlet is a point in a wiring system from which electrical power is taken to supply devices.
• Q79: What is a Socket?
  Ans: A socket is a device into which a plug is inserted to take electrical supply.
• Q80: What is a Two Pin Socket?
  Ans: A two pin socket is a socket with two holes used for connecting two-pin plugs for simple appliances.
• Q81: What is a Piano Type Socket?
  Ans: A piano type socket is a socket designed like a piano switch style, often combined with a switch for easy operation.
• Q82: What is a Three Pin Socket Outlet?
  Ans: A three pin socket outlet is a socket with three holes for live, neutral, and earth connections, providing better safety.
• Q83: What is a Round Socket Outlet?
  Ans: A round socket outlet is a circular-shaped socket used for connecting round pin plugs.
• Q84: What is a Plug? What is it used for?
  Ans: A plug is a device inserted into a socket to connect an electrical appliance to the power supply. It is used to draw electricity safely.
• Q85: What is a Two Pin Plug?
  Ans: A two pin plug has two pins for live and neutral connections and is used for low-power appliances.
• Q86: What is a Three Pin Plug?
  Ans: A three pin plug has three pins for live, neutral, and earth connections, providing better safety.
• Q87: What is Ceiling Rose?
  Ans: A ceiling rose is a device fixed on the ceiling used to connect and support a pendant lamp holder.
• Q88: What are Wall Brackets?
  Ans: Wall brackets are fittings attached to walls to support lamps or lighting fixtures.
• Q89: What is a Kit-Kat Fuse?
  Ans: A kit-kat fuse is a type of rewirable fuse used to protect circuits from overcurrent by melting the fuse wire.
• Q90: What is a Circuit Breaker?
  Ans: A circuit breaker is an automatic device that protects an electrical circuit by cutting off the supply when there is overload or short circuit.