FSc ICS Notes Physics XII Short Questions & Definitions Chapter 18 Electronics

FSc ICS Notes Physics XII Short Questions & Definitions Chapter 18 Electronics 2nd Year Physics Notes Online Taleem Ilmi Hub

If you want to view Exercise Question & Numerical Problems. Please refer to this page Physics Part 2

Electronics:

• The study and use of circuitry involving such components assemiconductors, resistors, capacitors, and inductors.
• The branch of Physics which is concerned with the emission, behaviour and effects of electrons.

Analogue: Pertaining to data that consists of continuously variable quantities.

Digital: Pertaining to data that consist of digits. Discrete not continuous.

Semiconductor: A material such as silicon or germanium, that has a resistivity midway between that of conductors and that of insulators.

Integrated circuit (IC): A circuit that incorporates numerous components into one unit.

Monolithic IC: A single chip of silicon is the base onto which all the individual components are integrated during manufacture and cannot be dismantled.

Hybrid IC: It consists of one or more monolithic ICs mounted on a base or several components similarly mounted and interconnected. After manufacture it cannot be dismantled.

Chip: A small piece of single crystal of semiconductor material containing either a single electronic component or an integrated circuit..

Black box: A unit whose internal structure is unknown but whose function is documented. It refers to circuits or to program code that performs a certain function. The internal mechanics of the function don’t matter to the reader.

Doping: The process of adding impurity to control the conductivity is called doping.

Impurities: In a semiconductor. Foreign atoms, either naturally occurring or deliberately introduced into the semiconductor. They have a fundamental effect on the amount and type of conductivity.

Trivalent impurity: Atoms used as impurity having three valence electrons in the outer most shell.

Pentavalent impurity: Atoms used as impurity having five valence electrons in the outer most shell.

P-n junction: The plane at which a P-type semiconductor crystal meets an N-type semiconductor crystal.

Depletion region (or Layer): A space-charge region in a semiconductor in which there is a net charge due to insufficient mobile charge carriers. They are formed at interface between a p-type and n-type semiconductor in the absence of an applied field.

Space-charge region: In any device, a region in which the net charge density is significantly different from zero.

Surface charge density: Amount of charge per unit area.

Volume charge density: Amount of charge per unit volume.

Potential barrier: The region in a field of force in which the potential is such that a particle, which is subject to the field, encounters opposition to its passage.

Forward biased: The potential applied across the p-n junction so as to decrease the height of the potential barrier, which facilitates the conduction of current.

Reverse biased: The potential applied across the p-n junction so as to increase the height of the potential barrier.

Cut-off bias: The smallest negative grid voltage for a given plate voltage, which causes a vacuum tube to cease to conduct.

Bias: Potential applied to electrode in an electronic device to produce desired characteristics.

Covalent bond: They are formed by sharing of valence electrons rather than by transfer.

Grid: In an electronic tube, an electrode used to control the flow of electrons from the cathode to the plate.

Grid bias: The grid to cathode voltage.

Reverse current (or Leakage current): Flowing of very small current across p-n junction,

due to flow of minority charge carriers when reverse biased of the junction.

P-n junction: The plane at which a P-type semiconductor crystal meets an N-type semiconductor crystal.

Semi-conductor diode: A semiconductor device, either based on semiconductor junction or on point contact, with two electrodes.

Rectification: The process of changing alternating current to direct current.

Rectifier: An electrical conductor that allows current to flow through it in one direction only, thus enabling the conversion of a.c. to d.c.

Half-wave rectification: Process in which only alternate half waves of the single- phase a.c. input wave are effective in delivering unidirectional current to the load.

Full-wave rectification: The process in which a circuit rectifies both the positive and negative half-cycles of the single-phase a.c. input and delivers unidirectional current to the load.

Light emitting diode (LED): A semiconductor diode, made from certain materials (e.g. gallium arsenide), in which light is emitted in response to the forward-bias current.

Photo diode: A semiconductor diode that produces a significant photo-current when illuminated.

Photo current: Current produced due to photo electric effect.

Photo voltaic cell: An electronic device that uses the photovoltaic effect to produce an emf. For example a solar cell.

Photovoltaic effect: An effect arising when a junction exists between two dissimilar materials and one of the materials is exposed to electromagnetic radiation, usually in the range near ultraviolet to infrared.

Gallium arsenide (GaAs) devices: Semiconductor devices based on the 3-5 semiconductor gallium arsenide. The semiconductor properties of GaAs give it several advantages over silicon for certain applications. For example, it has a high drift mobility, allowing it to be used for high speed applications such as high speed logic circuits.

Logic circuit: A circuit designed to perform a particular logical function based on the concepts of “and”, “either-or”, “neither-nor”, etc. Normally these circuits operate between two discrete voltage levels, i.e. high and low logic levels, and described as binary logic circuits.

Photovoltaic cell: An electronic device that uses the photovoltaic effect to produce an emf. For example, a solar cell.

Voltaic panels: Series-parallel arrays of photovoltaic cells, thousands in number, in the p-n junction, to obtain greater power from incident light.

Satellite: A smaller body that revolves around a larger body.

Solar energy: The energy produced by nuclear fusion and comprises almost entirely electromagnetic radiation.

Transistor:

• A transistor consists of a single crystal of germanium or silicon which is grown in such a way that it has three regions.
• A semiconductor device used as a substitute for vacuum tubes in electronic operations.

Base: The region in a bipolar junction transistor that separates the emitter and collector and to which the base electrode is attached.

Emitter: Region in a bipolar junction transistor from which carriers flow, through emitter junction, into the base. The electrode attached to this region is the emitter electrode.

Collector: The electrode in a transistor through which a primary flow of carriers leaves the inter-electrode region.

Carrier: An electron or hole that can move through a metal or semiconductor. carriers enable charge to be transported through a solid and are responsible for conductivity.

P-n-p transistor: A device taking central region as P-type region both sides of which junctions form with N-type crystals.

N-p-n transistor: A device taking central region as N-type region both sides of which junctions form with P-type crystals.

Current amplification factor: The ratio of the output current to the input current in a transistor.

Current gain (β): In a given transistor, the ratio of collector current IC to base current IB ; β = IC / IB

Amplifier: A device consisting of one or more vacuum tubes or transistors to increase the strength of a signal.

Microphone: A device for converting an acoustic signal into an electric signal. It forms the first element of the telephone, the broadcast transmitter, and all forms of electrical sound recorders.

Switch: A device for opening or closing a circuit or for changing its operating conditions between specified levels.

Capsule: A small case, container or vessel for enclosing something.

Operational amplifier (or Op-amp): A very high gain voltage amplifier, with very high input impedance, usually having its output voltage very much greater than the voltage difference between its two inputs.

Input resistance: It is the resistance between the positive and negative inputs of the amplifier. It has very high value.

Out put resistance: It is the resistance between the output terminal and ground in the amplifier. Its value is only a few ohms.

Open loop gain: It is the ratio of output voltage Vo to the voltage difference between non-inverting and inverting inputs when there is no external connection between the output and the inputs of the amplifier.

Inverting amplifier: In op-amps, the input signal that is to be amplified, is applied at inverting terminal through a resistance with certain potential. The non-inverting terminal is grounded having zero potential.

Non-inverting amplifier: In op-amps, the input signal is applied at non-inverting terminal. Due to high open loop gain, the inverting and non-inverting inputs are at the same potential. And input and output signals are in phase.

Comparator: A circuit, such as a differential amplifier, that compares two signals and produces an output that is a function of the result of the comparison.

Differential amplifier: A type of amplifier with two inputs, whose output is a function of the difference between the inputs.

Light dependent resistance (LDR): Such resistance whose value depends upon the intensity of light falling upon it.

Digital system: A system that deals with quantities or variables those have only two discrete values or states.

Manipulation: Working or operating skillfully. Experimental procedure or technique

Operation: A process in which a number, quantity, expression, etc. is altered or manipulated according to set formal rules, as those of addition, multiplication, differentiation, negation, etc.

Mathematics: The science that treats of quantities and magnitudes, by the use of symbols, and the measuring, relations, and properties of such quantities and magnitudes.

Algebra: The branch of mathematics which uses letters and other symbols instead of actual numbers and quantities for calculations.

Trigonometry: The study of triangles, and various relations of sides and angles of triangles.

Arithmetic: The branch of mathematics in which we use figures for calculations.

Boolean: Pertaining to, or described by an abstract system of postulates and symbols applicable to logical problems.

Algebra: The part of mathematics that uses letters and other symbols instead of actual numbers and quantities for calculations.

Logic circuit (or Logic gate):

• An electronic circuit that can be used to perform simple logical operations.
• An electronic circuit designed to perform a particular logical function based on the concepts of “and”, “either-or”, “neither-nor”, etc. Normally these circuits operate between two discrete voltage levels, i.e. high and low logic levels, and described as binary logic circuits.

Electronic circuit: A combination of electronic components that form a conducting path.

OR gate: A circuit with two or more inputs and one output whose output is high if any one or more of the inputs are high. Mathematical notation is: X = A + B

AND gate: A circuit with two or more inputs and one output in which the output signal is high if and only if all the inputs are high simultaneously. Mathematical notation is: X = A .B

NOT gate (or Inverter): A circuit with one input whose output is high if the input is low and vice versa. Mathematical notation is: X = A

NOR gate: A circuit with two or more inputs and one output, whose output is high if and only if all the inputs are low. Mathematical notation is: X = A + B

NAND gate: A circuit with two or more inputs and one output, whose output is high if any one or more of the inputs is low, and low if all the inputs are high. Mathematical notation is: X = A .B .

Exclusive OR gate(XOR): A circuit with two or more inputs and one output whose output is high if any one of the inputs is high. Mathematical notation is: X = A B + A B .

Exclusive NOR gate(XNOR): A circuit with two or more inputs and one output, whose output is high if two inputs are identical and low when two inputs are different. X = A B + A B .

Monitor: A device that observes and records selected activities within a system for analysis.

Parameter: A quantity that is constant in a given case but takes a particular value for each case considered.

Sensor: A device which detects or measures some condition or property and records, indicates, or otherwise responds to the information received.

Light dependent resistance (LDR): Such resistance whose value depends upon the intensity of light falling upon it.

Thermister: A semiconductor device that has a large negative temperature coefficient of resistance, and can be used for temperature measurement, or as a controlling element in electronic control circuits.

Vat: A tub, tank, cask, or other large vessel used to hold a liquid.

Written By: Asad Hussain