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c. Yai Sakizo (Developed the dry cell in 1887)b. Coulomb (SI unit of charge)c. Zinc container (Acts as the negative electrode)b. They will continue to work independently. (In a parallel circuit, appliances work independently)b. Miniature Circuit Breaker (MCB) (Detects slight voltage fluctuations, breaks circuit automatically, and can be reset)
positiveresistorneutronselectricalreversible
False (Pure water is an insulator, whereas impure water is a conductor)True (In series, if one appliance stops working, the circuit breaks and others stop working too)True (90% of outside lines are bare; weather coating provides no protection from electric shocks)False (Leclanche’s 1866 cell used a conducting solution/electrolyte, not a dry paste; dry paste was developed later for dry cells)True (This is the definition of potential difference)
Electric Current: The flow of charges caused by the movement of free electrons in a particular direction through a conductor, representing the amount of charge flowing per unit time.Conventional Current: The established practice of representing electric current as flowing from the positive terminal of a battery, through the circuit, to the negative terminal.Battery: A collection or combination of two or more electric cells connected in series (positive terminal of one connected to the negative terminal of the next).Insulators: Substances (such as plastic, rubber, wood, or glass) that do not allow electric current to flow through them easily.
Primary Cell vs. Secondary CellChemical Reaction: The chemical reaction inside a primary cell is irreversible, whereas inside a secondary cell, it is reversible.Reusability: A primary cell cannot be recharged and must be discarded after use, whereas a secondary cell can be recharged and reused.Examples: Primary cell examples include dry cells and Leclanche cells. Secondary cell examples include lead accumulators and lithium cylindrical cells.Series Circuit vs. Parallel CircuitVoltage: In a series circuit, there is a sharing of voltage (potential difference), whereas in a parallel circuit, each appliance gets the original voltage.Independence: In a series circuit, all appliances work simultaneously and depend on one another (if one breaks, all stop). In a parallel circuit, all appliances work independently (if one breaks, others continue working).
The mathematical relationship is:
Where 
is the electric current (in Amperes), 
is the charge (in Coulombs), and 
is the time (in seconds). One Ampere ( 
) is defined as one Coulomb of charge ( 
) flowing through a conductor in one second ( 
).Outside power lines are highly dangerous because 90% of them are actually bare, uninsulated wires. The dark coating is merely a weather coating, which provides no insulation or protection from electric shocks.The" dry cell is not completely dry because its electrolyte is a moist paste of ammonium chloride and plaster of Paris. It is called “dry” only because" the quantity of water is very small compared to liquid solution electrolytes.The turbine is rotated by flowing water (in hydro power plants) or steam/fossil fuels (in thermal plants) to provide the mechanical energy. The generator then converts this mechanical energy into electrical energy using magnetic fields.
It is an open circuit because the switch is in the open (off) position, creating a break in the electrical contact. The bulb will not glow because electric current cannot flow through an incomplete/broken path.Criteria for redrawn circuit diagram:Must use standard symbols: cell (parallel long and short lines, labeled + and -), closed switch (line completing the path/dots connected), bulb (loop inside a circle or standard resistor/bulb symbol), and connecting wires.Arrows must clearly point away from the positive terminal of the cell, through the closed switch and glowing bulb, and back to the negative terminal.
Construction of a Simple Dry Cell:Zinc Container: The outer body of the cell is made of a zinc container, which acts as the negative electrode (cathode). The bottom of this container serves as the negative terminal.Carbon Rod and Brass Cap: A carbon rod is placed at the center of the cell, acting as the positive electrode (anode). It is fitted with a brass cap at the top, which serves as the positive terminal.Chemical Mixture: The central carbon rod is surrounded by a mixture of manganese dioxide ( 
) and carbon ( 
) enclosed in a muslin bag.Electrolyte: The remaining space inside the zinc container is filled with a moist paste of ammonium chloride ( 
) and plaster of Paris, which acts as the electrolyte.Insulation: The outer sides of the zinc container are insulated with cardboard or plastic to prevent external leaks.
Electrical devices and old cells contain harmful, toxic chemicals and flammable substances. UN SDG 12 promotes responsible disposal and recycling of electrical waste (e-waste) to prevent these hazardous materials from contaminating the environment and ecosystems.You should always look for the ISI mark. This mark indicates that the electrical appliance has been certified as safe and reliable for household use.
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Prepared by: learnloophq@gmail.com
Chapter: 07. Electricity
SECTION A: MULTIPLE CHOICE QUESTIONS (MCQs)
SECTION B: FILL IN THE BLANKS
SECTION C: TRUE OR FALSE
SECTION D: EXPLANATION OF TERMS
SECTION E: IDENTIFYING AND DIFFERENTIATING CONCEPTS
SECTION F: SHORT ANSWER QUESTIONS
SECTION G: DIAGRAM-BASED QUESTIONS
SECTION H: LONG ANSWER QUESTIONS
SECTION I: ENVIRONMENTAL AWARENESS & EVERYDAY USE
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